CVE-2026-84367: CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in hapijs joi
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.
CVE-2026-84367: CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in hapijs joi
Description
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.
CVSS v3.1
Score 3.7low
Weaknesses
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-09-01T16:27:58.129Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a973b19acd9273b492feeaf
Added to database: 09/01/2026, 20:52:41 UTC
Last updated: 09/01/2026, 22:37:42 UTC
Views: 6
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