CVE-2026-843683.7LowCWE-1321

CVE-2026-84368: joi: Prototype pollution via a `proto` language key in custom messages

hapijs · joi

Affected: hapijs joi · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.4%probability of exploitation in the next 30 days

33rd percentile

050100

Higher than 33% of scored CVEs

3.7LowCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

hapijs · joi>= 16.0.0, <= 17.1.1; >= 17.2.0, < 17.13.6; >= 18.0.0, < 18.2.5

On the Atlas

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Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Prototype Pollution · Deserialization and Object Injection
Vendor: hapijs
Published: September 2026
Band: Unlikely (under 1%), September 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-84368 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.