CVE-2026-107301msgpack5: Partial options disable prototype protection
Updated under an hour ago ()
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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 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L
- Weakness (CWE)
- CWE-1321
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Oct 14, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
mcollina msgpack5 mcollina:msgpack5 (from the name) | before 6.1.0 | CNA record |
References
- https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6mx-refsource-confirm
- https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774x-refsource-misc
- https://github.com/mcollina/msgpack5/releases/tag/v6.1.0x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.