{"id":"CVE-2026-31865","aliases":["EUVD-2026-12749","GHSA-8hq9-phh3-p2wp"],"status":"published","title":"Elysia Cookie Value Prototype Pollution","description":"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.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00246,"percentile":0.15985,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1321"],"published":"2026-03-17T16:17:41Z","modified":"2026-10-28T02:30:48Z","fixes":[{"ecosystem":"npm","package":"elysia","fixed_in":["1.4.27"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"elysia","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.4.27"}]}]},{"source":"osv","ecosystem":"npm","package":"elysia","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.4.27"}]}]}],"products":[{"vendor":"elysiajs","product":"elysia"}],"references":[{"url":"https://github.com/elysiajs/elysia/security/advisories/GHSA-8hq9-phh3-p2wp","tags":["x_refsource_CONFIRM","Mitigation","Patch","Vendor Advisory","advisory","web"]},{"url":"https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aab","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31865","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-8hq9-phh3-p2wp"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31865.json","tags":["advisory"]},{"url":"https://github.com/elysiajs/elysia","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-31865","title":"Elysia Cookie Value Prototype Pollution","description":"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.","status":"published","published":"2026-03-18T02:50:55.403Z","modified":"2026-03-18T18:39:09.024Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:19:50.92611Z"}],"euvd":[{"id":"EUVD-2026-12749","description":"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.","status":"published","published":"2026-03-18T02:50:55Z","modified":"2026-03-18T18:39:09Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T19:25:32.813864Z"}],"ghsa":[{"id":"GHSA-8hq9-phh3-p2wp","title":"Elysia Cookie Value Prototype Pollution","description":"### Impact\nElysia cookie can be overridden by prototype pollution , eg. `__proto__`\n\nSending cookie with the follows name can override cookie value:\n```bash\n__proto__=%7B%22injected%22%3A%22polluted%22%7D\n```\n\n### Patches\nPatched by 1.4.27\n\n### Workarounds\n1. Use t.Cookie validation to enforce validation value\n2. Prevent iterable over cookie if possible","status":"published","published":"2026-03-17T16:17:41Z","modified":"2026-03-22T04:26:33Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:39:40.633038Z"}],"nvd":[{"id":"CVE-2026-31865","description":"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.","status":"published","published":"2026-03-18T04:17:19.393Z","modified":"2026-06-17T10:34:39.547Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:12:09.735529Z"}],"osv":[{"id":"CVE-2026-31865","title":"Elysia Cookie Value Prototype Pollution","description":"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.","status":"published","published":"2026-03-18T02:50:55.403Z","modified":"2026-10-28T02:30:48.508893301Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:45:01.218144Z"},{"id":"GHSA-8hq9-phh3-p2wp","title":"Elysia Cookie Value Prototype Pollution","description":"### Impact\nElysia cookie can be overridden by prototype pollution , eg. `__proto__`\n\nSending cookie with the follows name can override cookie value:\n```bash\n__proto__=%7B%22injected%22%3A%22polluted%22%7D\n```\n\n### Patches\nPatched by 1.4.27\n\n### Workarounds\n1. Use t.Cookie validation to enforce validation value\n2. Prevent iterable over cookie if possible","status":"published","published":"2026-03-17T16:17:41Z","modified":"2026-03-19T19:17:47.117772Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:46:42.437513Z"}]}}