EUVD-2026-69649Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
AV:N as the schema API is server-side and remotely reachable; AC:H for the non-default requirement of routing untrusted input into message configuration; I:L for prototype pollution enabling wrong-branch logic; C:N and A:N confirmed by the read/write-only nature of the impact.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
5DescriptionCVE.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.
AnalysisAI
Prototype pollution in joi, one of the most widely used JavaScript schema-validation libraries (versions 16.0.0 through <17.13.6 and <18.2.5, and @hapi/joi through 17.1.1), allows an attacker who can supply attacker-controlled language keys to joi's schema-construction message API to write arbitrary properties onto Object.prototype or the Object constructor's static properties. A language key named __proto__ contaminates the global prototype, causing every subsequent property-existence check on any plain object in the process to return an unexpected value, silently flipping conditional logic. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires an application to pass attacker-controlled values directly into joi's schema-construction message configuration as language keys - specifically via messages(), message(), prefs({ messages }), Joi.extend({ messages }), or rule({ message }). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS base score of 3.7 (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N) is well-calibrated for this vulnerability. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade joi to version 17.13.6 (for 17.x users) or 18.2.5 (for 18.x users); both are confirmed fixed releases per the GitHub Security Advisory GHSA-6w3j-5fw6-r9vr and the merged PRs at https://github.com/hapijs/joi/pull/3138 and https://github.com/hapijs/joi/pull/3139. … Detailed patch versions, workarounds, and compensating controls in full report. |
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