{"id":"CVE-2026-122131","title":"Joi 17.13.6 before 17.13.9 and 18.2.5 before 18.3.1 Prototype Replacement via __proto__ Language Key","summary":"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 …","severity":"low","cvss":3.7,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","cvssSource":"cna","cwe":["CWE-1321"],"vendor":"hapijs","product":"joi","affected":["joi >= 17.13.6 < 17.13.9","joi >= 18.2.5 < 18.3.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T19:39:47.724527Z"},"published":"2026-11-04","updated":"2026-11-05","sourceUpdated":"2026-11-05T19:40:15.094Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-122131","references":[{"url":"https://github.com/hapijs/joi/commit/76f5771e1afe527cfda24be0e1a920ffa54888d6","label":"Patch Commit"},{"url":"https://github.com/hapijs/joi"},{"url":"https://github.com/hapijs/joi/commit/dae9467cec27e787bfdea8b276595177d52d28ec"},{"url":"https://github.com/hapijs/joi/pull/3164"},{"url":"https://github.com/hapijs/joi/security/advisories/GHSA-6w3j-5fw6-r9vr","label":"GitHub Security Advisory (GHSA-6w3j-5fw6-r9vr)"},{"url":"https://github.com/hapijs/joi/blob/v18.3.0/lib/messages.js#L64-L67"},{"url":"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","label":"VulnCheck Advisory: Joi 17.13.6 before 17.13.9 and 18.2.5 before 18.3.1 Prototype Replacement via __proto__ Language Key"}],"tags":["cve.org"],"epss":0.0033,"epssPercentile":0.26253,"ingestedAt":"2026-11-05T22:38:31.556Z","slug":"CVE-2026-122131","body":"## Overview\n\nJoi 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.\n\n## Affected\n\n- `joi >= 17.13.6 < 17.13.9`\n- `joi >= 18.2.5 < 18.3.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":20,"depthScoreParts":{"impact":20.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}