CVE-2026-90771: joi messages compilation allows prototype replacement through __proto__ error codes
(updated )
joi before versions 17.13.8 and 18.2.9 contains a prototype pollution vulnerability in the messages compilation function that accepts proto as an error code. Attackers can supply proto keys in custom messages to replace the returned object’s prototype, breaking downstream code relying on Object.prototype methods.
References
- github.com/advisories/GHSA-wr44-6hxh-3jwq
- github.com/hapijs/joi
- github.com/hapijs/joi/blob/v18.2.8/lib/messages.js
- github.com/hapijs/joi/commit/1d2001cad9971327a62c9fd8eb1afec20cd784d2
- github.com/hapijs/joi/commit/5b8333c9177e08b4ef4ed02903c2d657084e7afb
- github.com/hapijs/joi/issues/3150
- github.com/hapijs/joi/pull/3151
- github.com/hapijs/joi/pull/3153
- github.com/hapijs/joi/releases/tag/v17.13.8
- github.com/hapijs/joi/releases/tag/v18.2.9
- nvd.nist.gov/vuln/detail/CVE-2026-90771
- www.vulncheck.com/advisories/joi-before-17.13.8-and-18.2.9-prototype-pollution-via-messages
Code Behaviors & Features
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