CWE-674
Allowed-with-ReviewUncontrolled Recursion
Abstraction: Class · Status: Draft
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
616 vulnerabilities reference this CWE, most recent first.
GHSA-R8RM-4HFJ-2X87
Vulnerability from github – Published: 2022-02-10 20:23 – Updated: 2021-04-22 16:58In Play Framework 2.6.0 through 2.8.2, data amplification can occur when an application accepts multipart/form-data JSON input.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "com.typesafe.play:play"
},
"ranges": [
{
"events": [
{
"introduced": "2.6.0"
},
{
"fixed": "2.7.6"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "com.typesafe.play:play"
},
"ranges": [
{
"events": [
{
"introduced": "2.8.0"
},
{
"fixed": "2.8.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2020-26882"
],
"database_specific": {
"cwe_ids": [
"CWE-674"
],
"github_reviewed": true,
"github_reviewed_at": "2021-04-22T16:58:02Z",
"nvd_published_at": "2020-11-06T14:15:00Z",
"severity": "HIGH"
},
"details": "In Play Framework 2.6.0 through 2.8.2, data amplification can occur when an application accepts multipart/form-data JSON input.",
"id": "GHSA-r8rm-4hfj-2x87",
"modified": "2021-04-22T16:58:02Z",
"published": "2022-02-10T20:23:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-26882"
},
{
"type": "WEB",
"url": "https://github.com/playframework/playframework/pull/10495"
},
{
"type": "WEB",
"url": "https://www.playframework.com/security/vulnerability/CVE-2020-26882-JsonParseDataAmplification"
}
],
"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": "Data Amplification in Play Framework"
}
GHSA-R9VW-MPPF-3883
Vulnerability from github – Published: 2022-08-11 00:00 – Updated: 2026-03-06 18:31Uncontrolled recursion in Unmarshal in encoding/xml before Go 1.17.12 and Go 1.18.4 allows an attacker to cause a panic due to stack exhaustion via unmarshalling an XML document into a Go struct which has a nested field that uses the 'any' field tag.
{
"affected": [],
"aliases": [
"CVE-2022-30633"
],
"database_specific": {
"cwe_ids": [
"CWE-674"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-08-10T20:15:00Z",
"severity": "HIGH"
},
"details": "Uncontrolled recursion in Unmarshal in encoding/xml before Go 1.17.12 and Go 1.18.4 allows an attacker to cause a panic due to stack exhaustion via unmarshalling an XML document into a Go struct which has a nested field that uses the \u0027any\u0027 field tag.",
"id": "GHSA-r9vw-mppf-3883",
"modified": "2026-03-06T18:31:09Z",
"published": "2022-08-11T00:00:18Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-30633"
},
{
"type": "WEB",
"url": "https://go.dev/cl/417061"
},
{
"type": "WEB",
"url": "https://go.dev/issue/53611"
},
{
"type": "WEB",
"url": "https://go.googlesource.com/go/+/c4c1993fd2a5b26fe45c09592af6d3388a3b2e08"
},
{
"type": "WEB",
"url": "https://groups.google.com/g/golang-announce/c/nqrv9fbR0zE"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RQXU752ALW53OJAF5MG3WMR5CCZVLWW6"
},
{
"type": "WEB",
"url": "https://pkg.go.dev/vuln/GO-2022-0523"
}
],
"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-RCR6-G7JC-F57G
Vulnerability from github – Published: 2026-05-18 20:37 – Updated: 2026-06-11 14:06Due to a missing depth check a stack overflow can occur in the fx operation by passing a crafted argument.
{
"affected": [
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-AnyCPU"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-HDRI-AnyCPU"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-HDRI-OpenMP-arm64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-HDRI-OpenMP-x64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-HDRI-arm64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-HDRI-x64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-HDRI-x86"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-OpenMP-arm64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-OpenMP-x64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-arm64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-x64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q16-x86"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q8-AnyCPU"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q8-OpenMP-arm64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q8-OpenMP-x64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q8-arm64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q8-x64"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Magick.NET-Q8-x86"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.13.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-46557"
],
"database_specific": {
"cwe_ids": [
"CWE-674"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-18T20:37:31Z",
"nvd_published_at": "2026-06-10T23:16:47Z",
"severity": "MODERATE"
},
"details": "Due to a missing depth check a stack overflow can occur in the fx operation by passing a crafted argument.",
"id": "GHSA-rcr6-g7jc-f57g",
"modified": "2026-06-11T14:06:07Z",
"published": "2026-05-18T20:37:31Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/ImageMagick/ImageMagick/security/advisories/GHSA-rcr6-g7jc-f57g"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46557"
},
{
"type": "PACKAGE",
"url": "https://github.com/ImageMagick/ImageMagick"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "ImageMagick: Stack overflow in fx operation"
}
GHSA-RF5R-VG7Q-HGM6
Vulnerability from github – Published: 2022-05-13 01:18 – Updated: 2022-05-13 01:18Mikrotik RouterOS before 6.42.7 and 6.40.9 is vulnerable to a stack exhaustion vulnerability. An authenticated remote attacker can crash the HTTP server via recursive parsing of JSON.
{
"affected": [],
"aliases": [
"CVE-2018-1158"
],
"database_specific": {
"cwe_ids": [
"CWE-674"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-08-23T19:29:00Z",
"severity": "MODERATE"
},
"details": "Mikrotik RouterOS before 6.42.7 and 6.40.9 is vulnerable to a stack exhaustion vulnerability. An authenticated remote attacker can crash the HTTP server via recursive parsing of JSON.",
"id": "GHSA-rf5r-vg7q-hgm6",
"modified": "2022-05-13T01:18:56Z",
"published": "2022-05-13T01:18:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-1158"
},
{
"type": "WEB",
"url": "https://mikrotik.com/download/changelogs"
},
{
"type": "WEB",
"url": "https://mikrotik.com/download/changelogs/bugfix-release-tree"
},
{
"type": "WEB",
"url": "https://www.tenable.com/security/research/tra-2018-21"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2019/Jul/20"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-RF62-M3FM-W623
Vulnerability from github – Published: 2022-05-17 03:54 – Updated: 2022-05-17 03:54Jansson 2.7 and earlier allows context-dependent attackers to cause a denial of service (deep recursion, stack consumption, and crash) via crafted JSON data.
{
"affected": [],
"aliases": [
"CVE-2016-4425"
],
"database_specific": {
"cwe_ids": [
"CWE-20",
"CWE-674"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2016-05-17T14:08:00Z",
"severity": "HIGH"
},
"details": "Jansson 2.7 and earlier allows context-dependent attackers to cause a denial of service (deep recursion, stack consumption, and crash) via crafted JSON data.",
"id": "GHSA-rf62-m3fm-w623",
"modified": "2022-05-17T03:54:54Z",
"published": "2022-05-17T03:54:54Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2016-4425"
},
{
"type": "WEB",
"url": "https://github.com/akheron/jansson/issues/282"
},
{
"type": "WEB",
"url": "https://github.com/akheron/jansson/pull/284"
},
{
"type": "WEB",
"url": "https://github.com/akheron/jansson/pull/284/commits/64ce0ad3731ebd77e02897b07920eadd0e2cc318"
},
{
"type": "WEB",
"url": "http://www.debian.org/security/2015/dsa-3577"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2016/05/01/5"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2016/05/02/1"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2016/05/03/3"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-RF74-V2FM-23PW
Vulnerability from github – Published: 2026-03-18 20:17 – Updated: 2026-03-18 20:17Summary
JSONTaggedDecoder.decode_obj() in nltk/jsontags.py calls itself
recursively without any depth limit. A deeply nested JSON structure
exceeding sys.getrecursionlimit() (default: 1000) will raise an
unhandled RecursionError, crashing the Python process.
Affected code
File: nltk/jsontags.py, lines 47–52
@classmethod
def decode_obj(cls, obj):
if isinstance(obj, dict):
obj = {key: cls.decode_obj(val) for (key, val) in obj.items()}
elif isinstance(obj, list):
obj = list(cls.decode_obj(val) for val in obj)
Proof of Concept
import sys, json
from nltk.jsontags import JSONTaggedDecoder
depth = sys.getrecursionlimit() + 50 # e.g. 1050
payload = '{"x":' * depth + "null" + "}" * depth
# Raises RecursionError, crashing the process
json.loads(payload, cls=JSONTaggedDecoder)
Impact
Any code path that passes externally-supplied JSON to
JSONTaggedDecoder is vulnerable to denial of service.
The severity depends on whether such a path exists in the
calling code (e.g. nltk/data.py).
Suggested Fix
Add a depth parameter with a hard limit:
@classmethod
def decode_obj(cls, obj, _depth=0):
if _depth > 100:
raise ValueError("JSON nesting too deep")
if isinstance(obj, dict):
obj = {key: cls.decode_obj(val, _depth + 1)
for (key, val) in obj.items()}
elif isinstance(obj, list):
obj = list(cls.decode_obj(val, _depth + 1) for val in obj)
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "nltk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "3.9.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-674"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-18T20:17:43Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "### Summary\n`JSONTaggedDecoder.decode_obj()` in `nltk/jsontags.py` calls itself \nrecursively without any depth limit. A deeply nested JSON structure \nexceeding `sys.getrecursionlimit()` (default: 1000) will raise an \nunhandled `RecursionError`, crashing the Python process.\n\n### Affected code\nFile: `nltk/jsontags.py`, lines 47\u201352\n```python\n@classmethod\ndef decode_obj(cls, obj):\n if isinstance(obj, dict):\n obj = {key: cls.decode_obj(val) for (key, val) in obj.items()}\n elif isinstance(obj, list):\n obj = list(cls.decode_obj(val) for val in obj)\n```\n\n### Proof of Concept\n```python\nimport sys, json\nfrom nltk.jsontags import JSONTaggedDecoder\n\ndepth = sys.getrecursionlimit() + 50 # e.g. 1050\npayload = \u0027{\"x\":\u0027 * depth + \"null\" + \"}\" * depth\n\n# Raises RecursionError, crashing the process\njson.loads(payload, cls=JSONTaggedDecoder)\n```\n\n### Impact\nAny code path that passes externally-supplied JSON to \n`JSONTaggedDecoder` is vulnerable to denial of service.\nThe severity depends on whether such a path exists in the \ncalling code (e.g. `nltk/data.py`).\n\n### Suggested Fix\nAdd a depth parameter with a hard limit:\n```python\n@classmethod\ndef decode_obj(cls, obj, _depth=0):\n if _depth \u003e 100:\n raise ValueError(\"JSON nesting too deep\")\n if isinstance(obj, dict):\n obj = {key: cls.decode_obj(val, _depth + 1) \n for (key, val) in obj.items()}\n elif isinstance(obj, list):\n obj = list(cls.decode_obj(val, _depth + 1) for val in obj)\n```",
"id": "GHSA-rf74-v2fm-23pw",
"modified": "2026-03-18T20:17:43Z",
"published": "2026-03-18T20:17:43Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-rf74-v2fm-23pw"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Natural Language Toolkit (NLTK) has unbounded recursion in JSONTaggedDecoder.decode_obj() may cause DoS"
}
GHSA-RMJ6-CH86-HM24
Vulnerability from github – Published: 2026-05-19 09:31 – Updated: 2026-05-19 09:31Uncontrolled Recursion vulnerability in Samsung Open Source Escargot allows Excessive Allocation.
This issue affects Escargot: 590345cc6258317c5da850d846ce6baaf2afc2d3.
{
"affected": [],
"aliases": [
"CVE-2026-47317"
],
"database_specific": {
"cwe_ids": [
"CWE-674"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-19T08:16:16Z",
"severity": "MODERATE"
},
"details": "Uncontrolled Recursion vulnerability in Samsung Open Source Escargot allows Excessive Allocation.\n\nThis issue affects Escargot: 590345cc6258317c5da850d846ce6baaf2afc2d3.",
"id": "GHSA-rmj6-ch86-hm24",
"modified": "2026-05-19T09:31:20Z",
"published": "2026-05-19T09:31:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-47317"
},
{
"type": "WEB",
"url": "https://github.com/Samsung/escargot/pull/1565"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-RMMF-6VG8-65GC
Vulnerability from github – Published: 2022-09-15 00:00 – Updated: 2022-09-18 00:00A vulnerability has been found in Nintendo Game Boy Color and classified as problematic. This vulnerability affects unknown code of the component Mobile Adapter GB. The manipulation leads to memory corruption. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used. VDB-208606 is the identifier assigned to this vulnerability.
{
"affected": [],
"aliases": [
"CVE-2022-3216"
],
"database_specific": {
"cwe_ids": [
"CWE-119",
"CWE-674"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-09-14T20:15:00Z",
"severity": "HIGH"
},
"details": "A vulnerability has been found in Nintendo Game Boy Color and classified as problematic. This vulnerability affects unknown code of the component Mobile Adapter GB. The manipulation leads to memory corruption. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used. VDB-208606 is the identifier assigned to this vulnerability.",
"id": "GHSA-rmmf-6vg8-65gc",
"modified": "2022-09-18T00:00:31Z",
"published": "2022-09-15T00:00:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-3216"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.208606"
},
{
"type": "WEB",
"url": "https://xcellerator.github.io/posts/tetsuji"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-RMMH-P597-PPVV
Vulnerability from github – Published: 2024-02-26 21:31 – Updated: 2026-04-24 20:36Showdownjs, versions <= 2.1.0, anchors subparser used to parse links has a nested regular expression which can lead to denial of service conditions given malicious input.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "showdown"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "2.1.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-1899"
],
"database_specific": {
"cwe_ids": [
"CWE-674",
"CWE-777"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-24T20:36:01Z",
"nvd_published_at": "2024-02-26T19:15:07Z",
"severity": "MODERATE"
},
"details": "Showdownjs, versions \u003c= 2.1.0, `anchors` subparser used to parse links has a nested regular expression which can lead to denial of service conditions given malicious input.",
"id": "GHSA-rmmh-p597-ppvv",
"modified": "2026-04-24T20:36:01Z",
"published": "2024-02-26T21:31:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-1899"
},
{
"type": "PACKAGE",
"url": "https://github.com/showdownjs/showdown"
},
{
"type": "WEB",
"url": "https://www.tenable.com/security/research/tra-2024-05"
}
],
"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:L",
"type": "CVSS_V3"
}
],
"summary": "Showdown vulnerable to Regular Expression Denial of Service (ReDoS) in link/anchor parsing"
}
GHSA-RV48-QQJ5-CRXG
Vulnerability from github – Published: 2026-07-15 17:44 – Updated: 2026-07-15 17:44Summary
Unbounded recursion depth in Protobuf.Decoder (Hex package protobuf, versions >= 0.8.0, < 0.16.1) lets an unauthenticated attacker crash any service that decodes untrusted protobuf messages whose schema contains a self-referential or cyclic message type. A small request body (a few KB to a few MB) that nests an embedded field hundreds of thousands to millions of levels deep forces the BEAM to recurse once per level, exhausting memory and pinning a scheduler. A handful of such requests can take the node offline (a request-amplification denial of service).
Details
Protobuf.Decoder.value_for_field/3 handles embedded message fields in its embedded?: true branch at lib/protobuf/decoder.ex:218-243. For an embedded field it calls decode(bin, type) recursively, which re-enters build_message → handle_value → value_for_field. The recursive call is not in tail position (its result is consumed by the surrounding decode after it returns), so every nesting level retains a live frame on the process stack and heap.
There is no recursion-depth counter anywhere in the decoder. For any schema with a self-referential message type (e.g. message Tree { Tree child = 1; }, a common shape for comment threads, org charts, file trees, and ASTs) or any cycle of message types, the attacker controls the nesting depth entirely through the input bytes. Each additional level costs only a 1-byte field tag plus a varint length prefix, so depth grows roughly inversely with payload size: a tiny body buys an enormous recursion depth.
Reference protobuf implementations (Google's C++, Java, etc.) cap recursion at 100 specifically to prevent this. The Elixir decoder enforces no comparable bound, so the recursion continues until the process exhausts memory, blows the stack, or starves the scheduler doing GC over the deep structure.
The fix threads a depth counter through decode / build_message / handle_value / value_for_field (or holds it in the process dictionary for the duration of the top-level decode) and raises Protobuf.DecodeError once it exceeds a configurable limit, defaulting to 100 to match the reference implementations.
PoC
- Define a self-referential schema:
defmodule Tree do use Protobuf, syntax: :proto3; field(:child, 1, type: Tree) end. - Build a wire-format body inner-to-outer: at each of
depthlevels prepend<<0x0A, length_varint(inner_size), inner>>(tag0x0A= field 1, wire type 2). Use an iolist with a running byte-size to keep generation O(depth). - POST the body (a few MB at
depth = 1_000_000) asapplication/x-protobufto any endpoint that callsTree.decode/1. - The non-tail
decode(bin, type)invalue_for_field/3re-enters once per nesting level, accumulating a frame per level. The decode burns seconds of CPU and hundreds of MB on the victim node; a few concurrent requests exhaust it.
Impact
Unauthenticated, network-reachable request-amplification denial of service against any service that decodes attacker-influenced protobuf bytes into a self-referential or cyclic message type. A single small request can consume seconds of CPU and hundreds of MB of memory on the victim; a few concurrent requests can take the node offline.
Resources
- Introduction commit: https://github.com/elixir-protobuf/protobuf/commit/21ec7c5bec4fec74e10c1de0d5d1a2d8152ac5d4
- Patch commit: https://github.com/elixir-protobuf/protobuf/commit/b8efa97790eece3d2d0e8e7c31a45ed409fe5338
{
"affected": [
{
"package": {
"ecosystem": "Hex",
"name": "protobuf"
},
"ranges": [
{
"events": [
{
"introduced": "0.8.0"
},
{
"fixed": "0.16.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-54451"
],
"database_specific": {
"cwe_ids": [
"CWE-674"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-15T17:44:28Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\n\nUnbounded recursion depth in `Protobuf.Decoder` (Hex package `protobuf`, versions `\u003e= 0.8.0, \u003c 0.16.1`) lets an unauthenticated attacker crash any service that decodes untrusted protobuf messages whose schema contains a self-referential or cyclic message type. A small request body (a few KB to a few MB) that nests an embedded field hundreds of thousands to millions of levels deep forces the BEAM to recurse once per level, exhausting memory and pinning a scheduler. A handful of such requests can take the node offline (a request-amplification denial of service).\n\n### Details\n\n`Protobuf.Decoder.value_for_field/3` handles embedded message fields in its `embedded?: true` branch at `lib/protobuf/decoder.ex:218-243`. For an embedded field it calls `decode(bin, type)` recursively, which re-enters `build_message \u2192 handle_value \u2192 value_for_field`. The recursive call is not in tail position (its result is consumed by the surrounding decode after it returns), so every nesting level retains a live frame on the process stack and heap.\n\nThere is no recursion-depth counter anywhere in the decoder. For any schema with a self-referential message type (e.g. `message Tree { Tree child = 1; }`, a common shape for comment threads, org charts, file trees, and ASTs) or any cycle of message types, the attacker controls the nesting depth entirely through the input bytes. Each additional level costs only a 1-byte field tag plus a varint length prefix, so depth grows roughly inversely with payload size: a tiny body buys an enormous recursion depth.\n\nReference protobuf implementations (Google\u0027s C++, Java, etc.) cap recursion at 100 specifically to prevent this. The Elixir decoder enforces no comparable bound, so the recursion continues until the process exhausts memory, blows the stack, or starves the scheduler doing GC over the deep structure.\n\nThe fix threads a depth counter through `decode / build_message / handle_value / value_for_field` (or holds it in the process dictionary for the duration of the top-level `decode`) and raises `Protobuf.DecodeError` once it exceeds a configurable limit, defaulting to 100 to match the reference implementations.\n\n### PoC\n\n1. Define a self-referential schema: `defmodule Tree do use Protobuf, syntax: :proto3; field(:child, 1, type: Tree) end`.\n2. Build a wire-format body inner-to-outer: at each of `depth` levels prepend `\u003c\u003c0x0A, length_varint(inner_size), inner\u003e\u003e` (tag `0x0A` = field 1, wire type 2). Use an iolist with a running byte-size to keep generation O(depth).\n3. POST the body (a few MB at `depth = 1_000_000`) as `application/x-protobuf` to any endpoint that calls `Tree.decode/1`.\n4. The non-tail `decode(bin, type)` in `value_for_field/3` re-enters once per nesting level, accumulating a frame per level. The decode burns seconds of CPU and hundreds of MB on the victim node; a few concurrent requests exhaust it.\n\n### Impact\n\nUnauthenticated, network-reachable request-amplification denial of service against any service that decodes attacker-influenced protobuf bytes into a self-referential or cyclic message type. A single small request can consume seconds of CPU and hundreds of MB of memory on the victim; a few concurrent requests can take the node offline. \n\n## Resources\n\n* Introduction commit: https://github.com/elixir-protobuf/protobuf/commit/21ec7c5bec4fec74e10c1de0d5d1a2d8152ac5d4\n* Patch commit: https://github.com/elixir-protobuf/protobuf/commit/b8efa97790eece3d2d0e8e7c31a45ed409fe5338",
"id": "GHSA-rv48-qqj5-crxg",
"modified": "2026-07-15T17:44:28Z",
"published": "2026-07-15T17:44:28Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/elixir-protobuf/protobuf/security/advisories/GHSA-rv48-qqj5-crxg"
},
{
"type": "WEB",
"url": "https://github.com/elixir-protobuf/protobuf/commit/21ec7c5bec4fec74e10c1de0d5d1a2d8152ac5d4"
},
{
"type": "WEB",
"url": "https://github.com/elixir-protobuf/protobuf/commit/b8efa97790eece3d2d0e8e7c31a45ed409fe5338"
},
{
"type": "PACKAGE",
"url": "https://github.com/elixir-protobuf/protobuf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Protobuf: Unbounded recursion depth in embedded-message decoding"
}
Mitigation
Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Mitigation
Increase the stack size.
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.