CVE-2024-30251: Aiohttp Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-5m98-qgg9-wh84
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CVSS 7.5
CWE-835
Published
Advisory Summary

CVE-2024-30251 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')) affecting Aiohttp libraries in the PyPI ecosystem. The issue involves aiohttp vulnerable to denial of service when trying to parse malformed post requests. Remediation is available by upgrading affected packages to version 3.9.4.

CVE-2024-30251 at a Glance

CVE Identifier CVE-2024-30251
GHSA Identifier GHSA-5m98-qgg9-wh84
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
Affected Product Aiohttp
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2024-30251

To remediate this vulnerability, upgrade all affected Aiohttp dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

aiohttp fixed: 3.9.4 
pip install aiohttp>=3.9.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show aiohttp

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2024-30251, inspect your installed packages using pip:

pip show aiohttp

Analyze the terminal output to locate any version of Aiohttp in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.9.4), your application is affected.

Note: The pip show aiohttp command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'), where the product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. In Aiohttp, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary An attacker can send a specially crafted POST (multipart/form-data) request. When the aiohttp server processes it, the server will enter an infinite loop and be unable to process any further requests. ### Impact An attacker can stop the application from serving requests after sending a single request. ------- For anyone needing to patch older versions of aiohttp, the minimum diff needed to resolve the issue is (located in `_read_chunk_from_length()`): ```diff diff --git a/aiohttp/multipart.py b/aiohttp/multipart.py index 227be605c..71fc2654a 100644 --- a/aiohttp/multipart.py +++ b/aiohttp/multipart.py @@ -338,6 +338,8 @@ class BodyPartReader: assert self._length is not None, "Content-Length required for chunked read" chunk_size = min(size, self._length - self._read_bytes) chunk = await self._content.read(chunk_size) + if self._content.at_eof(): + self._at_eof = True return chunk async def _read_chunk_from_stream(self, size: int) -> bytes: ``` This does however introduce some very minor issues with handling form data. So, if possible, it would be recommended to also backport the changes in: https://github.com/aio-libs/aiohttp/commit/cebe526b9c34dc3a3da9140409db63014bc4cf19 https://github.com/aio-libs/aiohttp/commit/7eecdff163ccf029fbb1ddc9de4169d4aaeb6597 https://github.com/aio-libs/aiohttp/commit/f21c6f2ca512a026ce7f0f6c6311f62d6a638866

CVE-2024-30251 Affected Aiohttp Versions

1 component(s)
Fixed Versions:
3.9.4
Product / Package Ecosystem Affected Versions Fixed Version
aiohttp
pypi/aiohttp
PyPI
< 3.9.4
3.9.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-5m98-qgg9-wh84
NVD — CVE-2024-30251 NVD
https://nvd.nist.gov/vuln/detail/CVE-2024-30251
Security Fix Commit FIX COMMIT
https://github.com/aio-libs/aiohttp/commit/7eecdff163ccf029fbb1ddc9de4169d4aaeb6597
Security Fix Commit FIX COMMIT
https://github.com/aio-libs/aiohttp/commit/cebe526b9c34dc3a3da9140409db63014bc4cf19
Security Fix Commit FIX COMMIT
https://github.com/aio-libs/aiohttp/commit/f21c6f2ca512a026ce7f0f6c6311f62d6a638866
Aiohttp Source Repository REPOSITORY
https://github.com/aio-libs/aiohttp
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2025/02/msg00002.html
Aiohttp Security Information SECURITY
http://www.openwall.com/lists/oss-security/2024/05/02/4

Frequently Asked Questions

What is CVE-2024-30251?
CVE-2024-30251 is a security vulnerability in Aiohttp involving aiohttp vulnerable to Denial of Service when trying to parse malformed POST requests under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop').
Which Aiohttp versions are affected?
Affected versions include releases prior to 3.9.4 across affected packages: aiohttp.
What version fixes CVE-2024-30251?
Upgrading to 3.9.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is aiohttp affected?
Yes, aiohttp is affected in releases prior to 3.9.4. Upgrade your dependency to 3.9.4 or later.
What is the CVSS score of CVE-2024-30251?
CVE-2024-30251 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2024-30251?
CVE-2024-30251 is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') (The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.).
How can I check PyPI dependencies for CVE-2024-30251?
Run the dependency tree command: 'pip show aiohttp'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5m98-qgg9-wh84",
  "modified" : "2025-11-03T22:46:13Z",
  "published" : "2024-05-03T17:29:54Z",
  "aliases" : [ "CVE-2024-30251" ],
  "summary" : "aiohttp vulnerable to Denial of Service when trying to parse malformed POST requests",
  "details" : "### Summary\nAn attacker can send a specially crafted POST (multipart/form-data) request. When the aiohttp server processes it, the server will enter an infinite loop and be unable to process any further requests.\n\n### Impact\nAn attacker can stop the application from serving requests after sending a single request.\n\n-------\n\nFor anyone needing to patch older versions of aiohttp, the minimum diff needed to resolve the issue is (located in `_read_chunk_from_length()`):\n\n```diff\ndiff --git a/aiohttp/multipart.py b/aiohttp/multipart.py\nindex 227be605c..71fc2654a 100644\n--- a/aiohttp/multipart.py\n+++ b/aiohttp/multipart.py\n@@ -338,6 +338,8 @@ class BodyPartReader:\n         assert self._length is not None, \"Content-Length required for chunked read\"\n         chunk_size = min(size, self._length - self._read_bytes)\n         chunk = await self._content.read(chunk_size)\n+        if self._content.at_eof():\n+            self._at_eof = True\n         return chunk\n \n     async def _read_chunk_from_stream(self, size: int) -> bytes:\n```\n\nThis does however introduce some very minor issues with handling form data. So, if possible, it would be recommended to also backport the changes in:\nhttps://github.com/aio-libs/aiohttp/commit/cebe526b9c34dc3a3da9140409db63014bc4cf19\nhttps://github.com/aio-libs/aiohttp/commit/7eecdff163ccf029fbb1ddc9de4169d4aaeb6597\nhttps://github.com/aio-libs/aiohttp/commit/f21c6f2ca512a026ce7f0f6c6311f62d6a638866",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "aiohttp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.9.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/security/advisories/GHSA-5m98-qgg9-wh84"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2024-30251"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/commit/7eecdff163ccf029fbb1ddc9de4169d4aaeb6597"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/commit/cebe526b9c34dc3a3da9140409db63014bc4cf19"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/commit/f21c6f2ca512a026ce7f0f6c6311f62d6a638866"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/aio-libs/aiohttp"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2025/02/msg00002.html"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2024/05/02/4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-835" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-05-03T17:29:54Z",
    "nvd_published_at" : "2024-05-02T14:15:09Z"
  }
}