CVE-2026-107301

Published: Oct 8, 2026Modified: Oct 14, 2026Deferred

6.5

Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L

Exploitability: 2.2 / Impact: 4.2

Source: security-advisories@github.com (Secondary)

Description

msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.

Related CWEs

CWE-1321

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

References (3)

https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774

Source: security-advisories@github.com

https://github.com/mcollina/msgpack5/releases/tag/v6.1.0

Source: security-advisories@github.com

https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6m

Source: security-advisories@github.com

Timeline

No history available yet.