CVE-2026-84368lowCWE-1321

CVE-2026-84368: low-severity vulnerability in hapijs joi

joi: Prototype pollution via a `__proto__` language key in custom messages

Published · Updated

Follow this CVE+ Monitor joi+ Monitor joi

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

8Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 3.7epss 0.4%
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.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Affected products
hapijs · joi
Related CVEs — hapijs joi

In the same product, most dangerous first.

CVE-2026-92599HIGHJoi before 17.13.7 and 18.2.6 ReDoS via isoDateEPSS 0.6%CVE-2026-48038MEDIUMjoi: Uncaught RangeError on deeply nested input through recursive `link()` schemasEPSS 0.5%CVE-2026-118772HIGHjoi: quadratic-time split in `string().email({ multiple: true })` allows denial of serviceEPSS 0.5%CVE-2026-90771MEDIUMjoi before 17.13.8 and 18.2.9 Prototype Pollution via messagesEPSS 0.4%CVE-2026-84367LOWjoi: object().rename() with a template target can set the validated object's prototypeEPSS 0.4%