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CVE-2025-66456

CVE-2025-66456 · Elysia vulnerable to prototype pollution with multiple standalone schema validation

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 9.1 · Critical · EPSS 0.6% · Fix available

Published
Updated

Stack: node

Affected products and versions

  • elysia

    Versions
    • >= 1.4.0, < 1.4.17: Affected

    No fix published

  • elysia npm

    Affected ranges
    • SEMVER: ≥ 1.4.0, < 1.4.17

    Update to 1.4.17

Original sources

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