joi is a schema description language and data validator for JavaScript. From 16.0.0 until 17.13.5 and 18.2.4, joi's lib/types/keys.js internals.rename() implementation used by object().rename() permits a schema that renames keys with a regular-expression source and a Joi.expression() or Joi.x() target that interpolates the pattern's own match data, combined with { multiple: true }, to derive a target from an attacker-controlled input key. An attacker can send x-__proto__ with an object value, causing the target to render as __proto__ and set the prototype of the object returned by validate() instead of creating an own key. The global Object.prototype is not modified, so the effect is confined to the object returned by that validation call. Static-string targets and schemas using the default { multiple: false } are not affected. This issue is fixed in versions 17.13.5 and 18.2.4.
References
Configurations
No configuration.
History
No history.
Information
Published : 2026-09-01 21:18
Updated : 2026-09-09 21:09
NVD link : CVE-2026-84367
Mitre link : CVE-2026-84367
CVE.ORG link : CVE-2026-84367
JSON object : View
Products Affected
No product.
CWE
CWE-1321
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
