{"id":"CVE-2026-34517","aliases":["GHSA-3wq7-rqq7-wx6j","PYSEC-2026-2099"],"url":"https://o3.security/vulnerability/CVE-2026-34517","summary":"AIOHTTP: Late size enforcement for non-file multipart fields causes memory DoS","details":"### Summary\n\nFor some multipart form fields, aiohttp read the entire field into memory before checking client_max_size.\n\n### Impact\n\nIf an application uses `Request.post()` an attacker can send a specially crafted multipart request to force significant temporary memory allocation even when the request is ultimately rejected.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145","published":"2026-04-01T20:14:15.830Z","modified":"2026-10-28T02:30:41.887868789Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"aiohttp","fixedVersion":"3.13.4"}],"fix":{"url":"https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145","label":"aio-libs/aiohttp@cbb774f"},"references":[{"type":"WEB","url":"https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34517.json"},{"type":"ADVISORY","url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-3wq7-rqq7-wx6j"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34517"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145"},{"type":"PACKAGE","url":"https://github.com/aio-libs/aiohttp"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:30:41.887868789Z"}}