{"id":"CVE-2026-8159","aliases":["GHSA-65x3-rw7q-gx94"],"url":"https://o3.security/vulnerability/CVE-2026-8159","summary":"multiparty vulnerable to ReDoS via filename parsing","details":"### Impact\n\nmultiparty@4.2.3 and lower versions are vulnerable to denial of service via regular expression backtracking in the `Content-Disposition` filename parameter parser. A multipart upload with a long header value containing `!filename=\"1` repeated can cause regex matching to take seconds, blocking the event loop. Any service accepting multipart uploads via multiparty is affected.\n\n### Patches\n\nUsers should upgrade to multiparty@4.3.0 or higher.\n\n### Workarounds\n\nNone. Limiting upload sizes at the proxy/gateway layer reduces but does not eliminate the attack surface, since a small ~8 KB header is sufficient to trigger the vulnerable backtracking.\n\n### Resources\n\n- [OWASP: Regular expression Denial of Service (ReDoS)](https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS)","published":"2026-05-12T08:35:39.564Z","modified":"2026-08-12T03:51:25.475402345Z","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":{"score":0.00335,"percentile":0.26267,"asOf":"2026-08-14"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"multiparty","fixedVersion":"4.3.0"}],"fix":null,"references":[{"type":"WEB","url":"https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS"},{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8159.json"},{"type":"ADVISORY","url":"https://github.com/pillarjs/multiparty/security/advisories/GHSA-65x3-rw7q-gx94"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-8159"},{"type":"PACKAGE","url":"https://github.com/pillarjs/multiparty"},{"type":"WEB","url":"https://github.com/pillarjs/multiparty/releases/tag/v4.3.0"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:25.475402345Z"}}