{"id":"CVE-2026-128127","summary":"AIOHTTP: Base64 multipart parts bypass client_max_size","details":"AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, BodyPartReader.read_chunk() processing a multipart part with Content-Transfer-Encoding set to base64 keeps reading until the chunk length is a multiple of four without enforcing a byte limit. A short Content-Length or a long run of whitespace can cause one call to read the remaining body into memory before the size check or spin on the event loop. A remote attacker can send such a multipart request to a handler that reads multipart data and bypass client_max_size. This issue is fixed in version 3.14.4.","aliases":["GHSA-24c4-3p7v-29cm"],"modified":"2026-11-14T10:45:48.837258496Z","published":"2026-11-13T20:30:19.198Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-400"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/128xxx/CVE-2026-128127.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/128xxx/CVE-2026-128127.json"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/commit/2d9c5c1062eff0034fb3ab120897a6c1b3ff7041"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/commit/a555ab698e08e9baea7386d5b4c0761cb8956fdd"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/pull/13509"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/pull/13513"},{"type":"WEB","url":"https://github.com/aio-libs/aiohttp/releases/tag/v3.14.4"},{"type":"ADVISORY","url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-24c4-3p7v-29cm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-128127"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/aio-libs/aiohttp","events":[{"introduced":"0"},{"fixed":"0c5e5e1c2256c2f46fa83912d01df7632c3b26cd"},{"fixed":"2d9c5c1062eff0034fb3ab120897a6c1b3ff7041"},{"fixed":"a555ab698e08e9baea7386d5b4c0761cb8956fdd"}],"database_specific":{"extracted_events":[{"source":"AFFECTED_FIELD","strategy":"StringRangeExpression","range":[{"introduced":"0"},{"fixed":"3.14.4"}]},{"range":[{"fixed":"2d9c5c1062eff0034fb3ab120897a6c1b3ff7041"}],"source":"REFERENCES_COMMIT"},{"range":[{"fixed":"a555ab698e08e9baea7386d5b4c0761cb8956fdd"}],"source":"REFERENCES_COMMIT"},{"source":"REFERENCES_TAG","original_tag":"v3.14.4","range":[{"fixed":"0c5e5e1c2256c2f46fa83912d01df7632c3b26cd"}]}]}}],"versions":["v3.14.3","v3.14.2","v3.14.1","v3.14.0","v3.13.0","v3.12.0","v3.12.0rc1","v3.12.0rc0","v3.12.0b3","v3.12.0b2","v3.12.0b1","v3.12.0b0","v3.11.0","v3.11.0rc2","v3.11.0rc1","v3.11.0rc0","v3.11.0b5","v3.11.0b4","v3.11.0b3","v3.11.0b2","v3.11.0b1","v3.11.0b0","v3.10.0","v3.10.0rc0","v3.10.0b1","v3.10.0b0","v3.9.0","v3.9.0rc0","v3.9.0b1","v3.9.0b0","v3.8.0","v3.7.1","v3.7.0","v3.7.0b1","v3.7.0b0","v3.6.2","v3.6.2a2","v3.6.2a1","v4.0.0a1","v3.6.1","v3.6.1b4","v3.6.1b3","v3.6.0","v3.6.0b0","v3.6.0a12","v3.6.0a11","v3.6.0a10","v3.6.0a9","v3.6.0a8","v3.6.0a7","v3.6.0a6","v3.6.0a5","v3.6.0a4","v3.6.0a3","v3.6.0a2","v3.6.0a1","v3.6.0a0","v3.5.4","v3.5.3","v3.5.2","v4.0.0a0","v3.5.1","v3.5.0","v3.5.0b3","v3.5.0b2","v3.5.0b1","v3.5.0a1","v3.4.0","v3.4.0b2","v3.4.0b1","v3.4.0a3","v3.4.0a0","v3.2.0","v3.1.0","v3.0.0b4","v3.0.0b3","v3.0.0b2","v3.0.0b1","v3.0.0b0","v2.3.0","v2.3.0a4","v2.3.0a3","v2.3.0a2","v2.3.0a1","v2.2.0","v2.1.0","2.0.0","2.0.0rc1","1.3.0","v1.2.0","v1.1.1","v1.1.0","v1.0.1","v1.0.0","v0.22.1","v0.22.0","v0.22.0b6","v0.22.0b5","v0.22.0b4","v0.22.0b3","v0.22.0b2","v0.22.0b1","v0.22.0b0","4v0.21.6","v0.21.0","v0.20.1","v0.20.0","v0.19.0","v0.18.0","v0.17.0","v0.16.3","v0.16.2","v0.16.1","v0.16.0","v0.15.3","0.15.2","v0.15.2","v0.15.1","v0.15.0","v0.14.4","v0.14.3","v0.14.2","v0.14.1","v0.14.0","v0.13.1","v0.13.0","v0.12.0","v0.11.0","v0.10.1","v0.10.0","v0.9.2","v0.9.1","v0.9.0","v0.8.4","v0.8.3","0.8.2","v0.8.1","v0.8.0","v0.7.3","v0.7.2","v0.7.1","v0.7.0","v.0.6.5","v0.6.4","v0.6.3","v0.6.2","v0.6.1","v0.5.0","v0.4.2","v0.4.1","v0.4","v0.3","v0.2","v0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-128127.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}