CVE-2024-30251: aiohttp vulnerable to Denial of Service when trying to parse malformed POST requests
Affects aiohttpSource GCVE Database
Not known to be exploited · CVSS 7.5 High : upgrade to 3.9.4 soon.
Data as of 29 Oct 2026, 22:52 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 7.5 |
|---|
- Patch
- Available – fixed in 3.9.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 3 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade aiohttp to 3.9.4.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| PyPIaiohttp | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### 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
References
- github.com/aio-libs/aiohttp/security/advisories/GHSA-5m98-qgg9-wh84 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2024-30251 (opens in a new tab)
- github.com/aio-libs/aiohttp/commit/7eecdff163ccf029fbb1ddc9de4169d4aaeb6597 (opens in a new tab)
- github.com/aio-libs/aiohttp/commit/cebe526b9c34dc3a3da9140409db63014bc4cf19 (opens in a new tab)
- github.com/aio-libs/aiohttp/commit/f21c6f2ca512a026ce7f0f6c6311f62d6a638866 (opens in a new tab)
- github.com/aio-libs/aiohttp (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/02/msg00002.html (opens in a new tab)
- openwall.com/lists/oss-security/2024/05/02/4 (opens in a new tab)