{"id":"CVE-2026-31865","aliases":["GHSA-8hq9-phh3-p2wp"],"url":"https://o3.security/vulnerability/CVE-2026-31865","summary":"Elysia Cookie Value Prototype Pollution","details":"Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.27, an Elysia cookie can be overridden by prototype pollution , eg. `__proto__`. This issue is patched in 1.4.27. As a workaround, use t.Cookie validation to enforce validation value and/or prevent iterable over cookie if possible.","published":"2026-03-18T02:50:55.403Z","modified":"2026-08-12T03:51:17.666159172Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"elysia","fixedVersion":"1.4.27"}],"fix":{"url":"https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aab","label":"elysiajs/elysia@e9d6b17"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31865.json"},{"type":"ADVISORY","url":"https://github.com/elysiajs/elysia/security/advisories/GHSA-8hq9-phh3-p2wp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31865"},{"type":"FIX","url":"https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aab"},{"type":"PACKAGE","url":"https://github.com/elysiajs/elysia"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:17.666159172Z"}}