medium6.5
CVE-2026-107301
msgpack5 is a msgpack v5 implementation for node.js and the browser.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | msgpack5 | < 6.1.0 | 6.1.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-8hq7-ggx2-cc6m
- https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6m
- https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774
- https://github.com/mcollina/msgpack5/releases/tag/v6.1.0