CVE-2026-122131
Joi 17.13.6 before 17.13.9 and 18.2.5 before 18.3.1 Prototype Replacement via __proto__ Language Key
CVSS Score
3.7
EPSS Score
0.0%
EPSS Percentile
0th
Joi 17.13.6 before 17.13.9 and 18.2.5 before 18.3.1 contains a prototype pollution vulnerability in lib/messages.js compile() and merge() that fails to reject a __proto__ language key. Attackers supplying untrusted message configuration via any().messages(), prefs, validate options or Joi.extend can replace the compiled messages prototype, altering or breaking validation error rendering and dependent logic.
| CWE | CWE-1321 |
| Vendor | hapijs |
| Product | joi |
| Published | Nov 4, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
hapijs / joi
17.13.6 < 17.13.9 18.2.5 < 18.3.1
References
github.com: https://github.com/hapijs/joi/commit/76f5771e1afe527cfda24be0e1a920ffa54888d6 github.com: https://github.com/hapijs/joi github.com: https://github.com/hapijs/joi/commit/dae9467cec27e787bfdea8b276595177d52d28ec github.com: https://github.com/hapijs/joi/pull/3164 github.com: https://github.com/hapijs/joi/security/advisories/GHSA-6w3j-5fw6-r9vr github.com: https://github.com/hapijs/joi/blob/v18.3.0/lib/messages.js#L64-L67 vulncheck.com: https://www.vulncheck.com/advisories/joi-17.13.6-before-17.13.9-and-18.2.5-before-18.3.1-prototype-replacement-via-proto-language-key
Credits
Zachariah Mithani (AploSec) Marsup