{"id":"CVE-2025-66456","revision":"486e35692fc743889e0d98da11a2b9a8","records":[{"revision":"486e35692fc743889e0d98da11a2b9a8","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-66456","aliases":[],"title":"Elysia vulnerable to prototype pollution with multiple standalone schema validation","description":"Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation and client-server communication. Versions 1.4.0 through 1.4.16 contain a prototype pollution vulnerability in `mergeDeep` after merging results of two standard schema validations with the same key. Due to the ordering of merging, there must be an any type that is set as a standalone guard, to allow for the `__proto__ prop` to be merged. When combined with GHSA-8vch-m3f4-q8jf this allows for a full RCE by an attacker. This issue is fixed in version 1.4.17. To workaround, remove the `__proto__ key` from body.","state":0,"publishedAt":"2025-12-09T19:43:10.252+00:00","modifiedAt":"2025-12-09T20:35:44.683+00:00","affected":[{"ecosystem":"Vendor product","name":"elysia","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"elysiajs\",\n                    \"product\": \"elysia\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 1.4.0, < 1.4.17\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","score":9.1,"severity":"CRITICAL"}],"references":["https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc","https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf","https://github.com/elysiajs/elysia/pull/1564","https://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51e","https://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e1574849e"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-66456","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-66456","identifiers":["CVE-2025-66456"]},"retained":false,"historicalAffected":[]}],"coverage":[]}