ghsa-3669-72x9-r9p3
Vulnerability from github
Details
Running schema.Decoder.Decode() on a struct that has a field of type []struct{...} opens it up to malicious attacks regarding memory allocations, taking advantage of the sparse slice functionality. For instance, in the Proof of Concept written below, someone can specify to set a field of the billionth element and it will allocate all other elements before it in the slice.
In the local environment environment for my project, I was able to call an endpoint like /innocent_endpoint?arr.10000000.X=1 and freeze my system from the memory allocation while parsing r.Form. I think this line is responsible for allocating the slice, although I haven't tested to make sure, so it's just an educated guess.
Proof of Concept
The following proof of concept works on both v1.2.0 and v1.2.1. I have not tested earlier versions.
```go package main
import ( "fmt"
"github.com/gorilla/schema"
)
func main() { dec := schema.NewDecoder() var result struct { Arr []struct{ Val int } } if err := dec.Decode(&result, map[string][]string{"arr.1000000000.Val": {"1"}}); err != nil { panic(err) } fmt.Printf("%#+v\n", result) }
```
Impact
Any use of schema.Decoder.Decode() on a struct with arrays of other structs could be vulnerable to this memory exhaustion vulnerability. There seems to be no possible solution that a developer using this library can do to disable this behaviour without fixing it in this project, so all uses of Decode that fall under this umbrella are affected. A fix that doesn't require a major change may also be harder to find, since it could break compatibility with some other intended use-cases.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/gorilla/schema"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.4.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-37298"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2024-07-01T20:35:12Z",
"nvd_published_at": "2024-07-01T19:15:04Z",
"severity": "HIGH"
},
"details": "### Details\n\nRunning `schema.Decoder.Decode()` on a struct that has a field of type `[]struct{...}` opens it up to malicious attacks regarding memory allocations, taking advantage of the sparse slice functionality. For instance, in the Proof of Concept written below, someone can specify to set a field of the billionth element and it will allocate all other elements before it in the slice. \n\nIn the local environment environment for my project, I was able to call an endpoint like `/innocent_endpoint?arr.10000000.X=1` and freeze my system from the memory allocation while parsing `r.Form`. I think [this line](https://github.com/gorilla/schema/blob/main/decoder.go#L223) is responsible for allocating the slice, although I haven\u0027t tested to make sure, so it\u0027s just an educated guess.\n\n### Proof of Concept\n\nThe following proof of concept works on both v1.2.0 and v1.2.1. I have not tested earlier versions.\n\n```go\npackage main\n\nimport (\n\t\"fmt\"\n\n\t\"github.com/gorilla/schema\"\n)\n\nfunc main() {\n\tdec := schema.NewDecoder()\n\tvar result struct {\n\t\tArr []struct{ Val int }\n\t}\n\tif err := dec.Decode(\u0026result, map[string][]string{\"arr.1000000000.Val\": {\"1\"}}); err != nil {\n\t\tpanic(err)\n\t}\n\tfmt.Printf(\"%#+v\\n\", result)\n}\n\n```\n\n### Impact\n\nAny use of `schema.Decoder.Decode()` on a struct with arrays of other structs could be vulnerable to this memory exhaustion vulnerability. There seems to be no possible solution that a developer using this library can do to disable this behaviour without fixing it in this project, so all uses of Decode that fall under this umbrella are affected. A fix that doesn\u0027t require a major change may also be harder to find, since it could break compatibility with some other intended use-cases.\n",
"id": "GHSA-3669-72x9-r9p3",
"modified": "2024-07-05T21:29:07Z",
"published": "2024-07-01T20:35:12Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/gorilla/schema/security/advisories/GHSA-3669-72x9-r9p3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-37298"
},
{
"type": "WEB",
"url": "https://github.com/gorilla/schema/commit/cd59f2f12cbdfa9c06aa63e425d1fe4a806967ff"
},
{
"type": "PACKAGE",
"url": "https://github.com/gorilla/schema"
},
{
"type": "WEB",
"url": "https://github.com/gorilla/schema/blob/main/decoder.go#L223"
}
],
"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": "Potential memory exhaustion attack due to sparse slice deserialization"
}
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.