CVE-2025-66456
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.56%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 4.0
- 9.1 CRITICALCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.56% probability · 45th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-1321
- Affected
- elysiajs/elysia
- Source
- security-advisories@github.com
References
- https://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51ePatch
- https://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e1574849ePatch
- https://github.com/elysiajs/elysia/pull/1564Issue Tracking, Patch
- https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jfNot Applicable
- https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2ccExploit, Patch, Vendor Advisory
- https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jfNot Applicable
- https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2ccExploit, Patch, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.