{"id":"GHSA-qxch-whhj-8956","summary":"multiparty: Denial of Service via Prototype Pollution leads to Uncaught Exception","details":"### Impact\n\nmultiparty@4.2.3 and lower versions are vulnerable to denial of service via uncaught exception. By sending a `multipart/form-data` request with a field name that collides with an inherited `Object.prototype` property (e.g., `__proto__`, `constructor`, `toString`), the parser invokes `.push()` on the inherited prototype value rather than an array, throwing a `TypeError` that propagates as an uncaught exception and crashes the process. 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.","aliases":["CVE-2026-8161"],"modified":"2026-05-18T17:45:09.421560698Z","published":"2026-05-18T17:35:01Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-05-18T17:35:01Z","nvd_published_at":"2026-05-12T10:16:48Z","cwe_ids":["CWE-1321","CWE-248"],"severity":"HIGH"},"references":[{"type":"WEB","url":"https://github.com/pillarjs/multiparty/security/advisories/GHSA-qxch-whhj-8956"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-8161"},{"type":"WEB","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"PACKAGE","url":"https://github.com/pillarjs/multiparty"},{"type":"WEB","url":"https://github.com/pillarjs/multiparty/releases/tag/v4.3.0"}],"affected":[{"package":{"name":"multiparty","ecosystem":"npm","purl":"pkg:npm/multiparty"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.3.0"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 4.2.3","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-qxch-whhj-8956/GHSA-qxch-whhj-8956.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}