Описание
joi: Prototype pollution via a __proto__ language key in custom messages
Impact
An application that passes attacker-controlled data into joi's custom message configuration (messages(), message(), prefs({ messages }), Joi.extend({ messages }) or rule({ message })) lets the attacker write properties onto Object.prototype, where every object in the process then inherits them. A key named __proto__ was treated as a language name, and the code reused the object it found at that key, which resolves to the prototype rather than to a new own property; a key named constructor did the same to the Object function's statics. A consuming application that gates on the mere presence of a property (if (user.isAdmin)) can be made to take the wrong branch for every object it inspects.
This is not reachable from data that joi validates. Custom messages are schema-construction configuration, normally written by the application developer. Exploitation therefore requires an application that feeds untrusted input straight into schema construction.
Patches
Upgrade to version 18.2.5 or 17.13.6.
Workarounds
Do not pass untrusted input into messages(), message(), prefs({ messages }), Joi.extend({ messages }) or rule({ message }). Or validate that they don't contain any __proto__ or constructor property.
Ссылки
- https://github.com/hapijs/joi/security/advisories/GHSA-6w3j-5fw6-r9vr
- https://nvd.nist.gov/vuln/detail/CVE-2026-84368
- https://github.com/hapijs/joi/pull/3138
- https://github.com/hapijs/joi/pull/3139
- https://github.com/hapijs/joi/commit/8d0b808f3e874d28f9078f61b7742290989afb36
- https://github.com/hapijs/joi/commit/90d07571923c90e3432a328fc041d1cda03d30fa
Пакеты
joi
>= 17.2.0, < 17.13.6
17.13.6
@hapi/joi
>= 16.0.0, <= 17.1.1
Отсутствует
joi
>= 18.0.0, < 18.2.5
18.2.5
Связанные уязвимости
joi is a schema description language and data validator for JavaScript. From 16.0.0 until 17.13.6 and 18.2.5, the @hapi/joi package through 17.1.1 and the successor joi package contain prototype pollution in lib/messages.js, where exports.compile() and exports.merge() reuse inherited objects for attacker-controlled language keys supplied through messages(), message(), prefs({ messages }), Joi.extend({ messages }), or rule({ message }). A language key named __proto__ writes properties onto Object.prototype, and constructor writes to the Object function's static properties. A consuming application that gates on the presence of an inherited property can take the wrong branch for every inspected object. The flaw is not reachable from data that joi validates and requires an application to feed untrusted input directly into schema-construction configuration. This issue is fixed in joi versions 17.13.6 and 18.2.5; no fixed @hapi/joi version is available.
joi is a schema description language and data validator for JavaScript. From 16.0.0 until 17.13.6 and 18.2.5, the @hapi/joi package through 17.1.1 and the successor joi package contain prototype pollution in lib/messages.js, where exports.compile() and exports.merge() reuse inherited objects for attacker-controlled language keys supplied through messages(), message(), prefs({ messages }), Joi.extend({ messages }), or rule({ message }). A language key named __proto__ writes properties onto Object.prototype, and constructor writes to the Object function's static properties. A consuming application that gates on the presence of an inherited property can take the wrong branch for every inspected object. The flaw is not reachable from data that joi validates and requires an application to feed untrusted input directly into schema-construction configuration. This issue is fixed in joi versions 17.13.6 and 18.2.5; no fixed @hapi/joi version is available.