id: PYSEC-2026-1098
published: "2026-07-07T11:45:40.794194Z"
modified: "2026-07-07T17:23:35.984420Z"
aliases:
- CVE-2024-30251
- GHSA-5m98-qgg9-wh84
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"
affected:
- package:
    name: aiohttp
    ecosystem: PyPI
    purl: pkg:pypi/aiohttp
  ranges:
  - type: ECOSYSTEM
    events:
    - introduced: "0"
    - fixed: 3.9.4
  versions:
  - "0.1"
  - 0.10.0
  - 0.10.1
  - 0.10.2
  - 0.11.0
  - 0.12.0
  - 0.13.0
  - 0.13.1
  - 0.14.0
  - 0.14.1
  - 0.14.2
  - 0.14.3
  - 0.14.4
  - 0.15.0
  - 0.15.1
  - 0.15.2
  - 0.15.3
  - 0.16.0
  - 0.16.1
  - 0.16.2
  - 0.16.3
  - 0.16.4
  - 0.16.5
  - 0.16.6
  - 0.17.0
  - 0.17.1
  - 0.17.2
  - 0.17.3
  - 0.17.4
  - 0.18.0
  - 0.18.1
  - 0.18.2
  - 0.18.3
  - 0.18.4
  - 0.19.0
  - "0.2"
  - 0.20.0
  - 0.20.1
  - 0.20.2
  - 0.21.0
  - 0.21.1
  - 0.21.2
  - 0.21.4
  - 0.21.5
  - 0.21.6
  - 0.22.0
  - 0.22.0a0
  - 0.22.0b0
  - 0.22.0b1
  - 0.22.0b2
  - 0.22.0b3
  - 0.22.0b4
  - 0.22.0b5
  - 0.22.0b6
  - 0.22.1
  - 0.22.2
  - 0.22.3
  - 0.22.4
  - 0.22.5
  - "0.3"
  - "0.4"
  - 0.4.1
  - 0.4.2
  - 0.4.3
  - 0.4.4
  - 0.5.0
  - 0.6.0
  - 0.6.1
  - 0.6.2
  - 0.6.3
  - 0.6.4
  - 0.6.5
  - 0.7.0
  - 0.7.1
  - 0.7.2
  - 0.7.3
  - 0.8.0
  - 0.8.1
  - 0.8.2
  - 0.8.3
  - 0.8.4
  - 0.9.0
  - 0.9.1
  - 0.9.2
  - 0.9.3
  - 1.0.0
  - 1.0.1
  - 1.0.2
  - 1.0.3
  - 1.0.5
  - 1.1.0
  - 1.1.1
  - 1.1.2
  - 1.1.3
  - 1.1.4
  - 1.1.5
  - 1.1.6
  - 1.2.0
  - 1.3.0
  - 1.3.1
  - 1.3.2
  - 1.3.3
  - 1.3.4
  - 1.3.5
  - 2.0.0
  - 2.0.0rc1
  - 2.0.1
  - 2.0.2
  - 2.0.3
  - 2.0.4
  - 2.0.5
  - 2.0.6
  - 2.0.7
  - 2.1.0
  - 2.2.0
  - 2.2.1
  - 2.2.2
  - 2.2.3
  - 2.2.4
  - 2.2.5
  - 2.3.0
  - 2.3.0a1
  - 2.3.0a2
  - 2.3.0a3
  - 2.3.0a4
  - 2.3.1
  - 2.3.10
  - 2.3.1a1
  - 2.3.2
  - 2.3.2b2
  - 2.3.2b3
  - 2.3.3
  - 2.3.4
  - 2.3.5
  - 2.3.6
  - 2.3.7
  - 2.3.8
  - 2.3.9
  - 3.0.0
  - 3.0.0b0
  - 3.0.0b1
  - 3.0.0b2
  - 3.0.0b3
  - 3.0.0b4
  - 3.0.1
  - 3.0.2
  - 3.0.3
  - 3.0.4
  - 3.0.5
  - 3.0.6
  - 3.0.7
  - 3.0.8
  - 3.0.9
  - 3.1.0
  - 3.1.1
  - 3.1.2
  - 3.1.3
  - 3.2.0
  - 3.2.1
  - 3.3.0
  - 3.3.0a0
  - 3.3.1
  - 3.3.2
  - 3.3.2a0
  - 3.4.0
  - 3.4.0a0
  - 3.4.0a3
  - 3.4.0b1
  - 3.4.0b2
  - 3.4.1
  - 3.4.2
  - 3.4.3
  - 3.4.4
  - 3.5.0
  - 3.5.0a1
  - 3.5.0b1
  - 3.5.0b2
  - 3.5.0b3
  - 3.5.1
  - 3.5.2
  - 3.5.3
  - 3.5.4
  - 3.6.0
  - 3.6.0a0
  - 3.6.0a1
  - 3.6.0a11
  - 3.6.0a12
  - 3.6.0a2
  - 3.6.0a3
  - 3.6.0a4
  - 3.6.0a5
  - 3.6.0a6
  - 3.6.0a7
  - 3.6.0a8
  - 3.6.0a9
  - 3.6.0b0
  - 3.6.1
  - 3.6.1b3
  - 3.6.1b4
  - 3.6.2
  - 3.6.2a0
  - 3.6.2a1
  - 3.6.2a2
  - 3.6.3
  - 3.7.0
  - 3.7.0b0
  - 3.7.0b1
  - 3.7.1
  - 3.7.2
  - 3.7.3
  - 3.7.4
  - 3.7.4.post0
  - 3.8.0
  - 3.8.0a7
  - 3.8.0b0
  - 3.8.1
  - 3.8.2
  - 3.8.3
  - 3.8.4
  - 3.8.5
  - 3.8.6
  - 3.9.0
  - 3.9.0b0
  - 3.9.0b1
  - 3.9.0rc0
  - 3.9.1
  - 3.9.2
  - 3.9.3
  - 3.9.4rc0
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
- type: PACKAGE
  url: https://pypi.org/project/aiohttp
- type: ADVISORY
  url: https://github.com/advisories/GHSA-5m98-qgg9-wh84
severity:
- type: CVSS_V3
  score: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H