{"id":"PYSEC-2026-1096","summary":"aiohttp has a memory leak when middleware is enabled when requesting a resource with a non-allowed method","details":"### Summary\n\nA memory leak can occur when a request produces a `MatchInfoError`. This was caused by adding an entry to a cache on each request, due to the building of each `MatchInfoError` producing a unique cache entry.\n\n### Impact\n\nIf the user is making use of any middlewares with `aiohttp.web` then it is advisable to upgrade immediately.\n\nAn attacker may be able to exhaust the memory resources of a server by sending a substantial number (100,000s to millions) of such requests.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/bc15db61615079d1b6327ba42c682f758fa96936","aliases":["CVE-2024-52303","GHSA-27mf-ghqm-j3j8"],"modified":"2026-07-07T17:46:18.681380663Z","published":"2026-07-07T14:34:45.010533Z","references":[{"type":"WEB","url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-27mf-ghqm-j3j8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-52303"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/commit/bc15db61615079d1b6327ba42c682f758fa96936"},{"type":"PACKAGE","url":"https://github.com/aio-libs/aiohttp"},{"type":"PACKAGE","url":"https://pypi.org/project/aiohttp"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-27mf-ghqm-j3j8"}],"affected":[{"package":{"name":"aiohttp","ecosystem":"PyPI","purl":"pkg:pypi/aiohttp"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.10.6"},{"fixed":"3.10.11"}]}],"versions":["3.10.10","3.10.11rc0","3.10.6","3.10.7","3.10.8","3.10.9"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/aiohttp/PYSEC-2026-1096.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"}]}