{"id":"CVE-2026-42561","aliases":["GHSA-pp6c-gr5w-3c5g","PYSEC-2026-3039"],"url":"https://o3.security/vulnerability/CVE-2026-42561","summary":"Python-Multipart: Denial of Service via unbounded multipart part headers","details":"Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.27, python-multipart has a denial of service vulnerability in multipart part header parsing. When parsing multipart/form-data, MultipartParser previously had no limit on the number of part headers or the size of an individual part header. An attacker could send a request with either many repeated headers without terminating the header block or a single very large header value, causing excessive CPU work before request rejection or completion. This vulnerability is fixed in 0.0.27.","published":"2026-05-13T20:55:11.767Z","modified":"2026-08-09T03:30:50.873790928Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"python-multipart","fixedVersion":"0.0.27"}],"fix":null,"references":[{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42561.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:37275"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:42132"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:42142"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:43038"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:44696"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:51194"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:51219"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:51357"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-42561"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42561.json"},{"type":"ADVISORY","url":"https://github.com/Kludex/python-multipart/security/advisories/GHSA-pp6c-gr5w-3c5g"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42561"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2477309"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-09T03:30:50.873790928Z"}}