Bug 2567736 (CVE-2026-122131)

Summary: CVE-2026-122131 joi: joi: Prototype pollution via untrusted message configuration
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in joi. Applications that pass untrusted input into custom message configuration functions allow an attacker to cause prototype pollution, where shared base object properties in the runtime environment are improperly altered. By supplying a specially crafted message configuration containing reserved object keys, an attacker can modify prototype properties, potentially disrupting application behavior and corrupting validation logic.
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Description OSIDB Bzimport 2026-11-05 22:22:06 UTC 
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.