CVE-2025-66456
Published: Dec 9, 2025
Modified: Dec 9, 2025
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.
| Vendor | Product | Versions |
|---|---|---|
elysiajs | elysia | affected >= 1.4.0, < 1.4.17 |
Weaknesses (CWE)
References
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