Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') Affecting unleash package, versions <8.2.0-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.26% (17th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-UNLEASH-19686089
  • published11 Sept 2026
  • disclosed1 Sept 2026

Introduced: 1 Sep 2026

NewCVE-2026-84368  (opens in a new tab)
CWE-1321  (opens in a new tab)

How to fix?

Upgrade Chainguard unleash to version 8.2.0-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream unleash package and not the unleash package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

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 Base Scores

version 3.1