{"id":"CVE-2024-30251","aliases":["GHSA-5m98-qgg9-wh84","PYSEC-2026-1098"],"title":"aiohttp vulnerable to Denial of Service when trying to parse malformed POST requests","summary":"aiohttp vulnerable to Denial of Service when trying to parse malformed POST requests","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","vendor":"aiohttp","product":"aiohttp","ecosystem":"pip","affected":["aiohttp < 3.9.4"],"patched":["aiohttp 3.9.4"],"published":"2024-05-03","updated":"2026-09-10","sourceUpdated":"2026-09-10T03:50:13.407749365Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-5m98-qgg9-wh84","references":[{"url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-5m98-qgg9-wh84"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2024-30251"},{"url":"https://github.com/aio-libs/aiohttp/commit/7eecdff163ccf029fbb1ddc9de4169d4aaeb6597"},{"url":"https://github.com/aio-libs/aiohttp/commit/cebe526b9c34dc3a3da9140409db63014bc4cf19"},{"url":"https://github.com/aio-libs/aiohttp/commit/f21c6f2ca512a026ce7f0f6c6311f62d6a638866"},{"url":"https://github.com/aio-libs/aiohttp"},{"url":"https://lists.debian.org/debian-lts-announce/2025/02/msg00002.html"},{"url":"http://www.openwall.com/lists/oss-security/2024/05/02/4"}],"tags":["osv","pip"],"epss":0.01094,"epssPercentile":0.64086,"ingestedAt":"2026-07-08T18:25:46.033Z","slug":"CVE-2024-30251","body":"## Overview\n\n### 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\n\n## Affected packages\n\n- `aiohttp < 3.9.4`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `aiohttp 3.9.4`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}