{"id":"CVE-2026-40347","aliases":["GHSA-mj87-hwqh-73pj","PYSEC-2026-3038"],"url":"https://o3.security/vulnerability/CVE-2026-40347","summary":"Python-Multipart affected by Denial of Service via large multipart preamble or epilogue data","details":"Python-Multipart is a streaming multipart parser for Python. Versions prior to 0.0.26 have a denial of service vulnerability when parsing crafted `multipart/form-data` requests with large preamble or epilogue sections. Upgrade to version 0.0.26 or later, which skips ahead to the next boundary candidate when processing leading CR/LF data and immediately discards epilogue data after the closing boundary.","published":"2026-04-17T23:56:50.777Z","modified":"2026-08-07T11:49:13.912765098Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"python-multipart","fixedVersion":"0.0.26"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/Kludex/python-multipart/releases/tag/0.0.26"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40347.json"},{"type":"ADVISORY","url":"https://github.com/Kludex/python-multipart/security/advisories/GHSA-mj87-hwqh-73pj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40347"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:49:13.912765098Z"}}