CVE-2026-107301
mediummsgpack5 is a msgpack v5 implementation for node.js and the browser.
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.
CVSS
6.5
6.5 (CVSS v3.1)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L Severity source: NVD CVSS v3.1 (security-advisories@github.com)
Timeline (UTC)
Published: 2026-10-08 17:17
Modified: 2026-10-14 01:17
NVD status: Deferred
Last synced 2 days ago
Verified against the source API 2026-10-27 06:58 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774 security-advisories@github.com
- https://github.com/mcollina/msgpack5/releases/tag/v6.1.0 security-advisories@github.com
- https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6m security-advisories@github.com
Data sources
NVD CVE API 2.0 — fetched 2026-10-27 06:58 UTC · record ↗