Vulnerability Description
protobufjs compiles protobuf definitions into JavaScript (JS) functions. From 8.2.0 until 8.6.5, the protobufjs Text Format extension parsed string-keyed map entries using ordinary property assignment, allowing a map entry with key __proto__ to change the prototype of the returned map object instead of creating an own map entry in protobufjs/ext/textformat. This issue is fixed in version 8.6.5.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Protobufjs Project | Protobufjs | >= 8.2.0, < 8.6.5 |
Related Weaknesses (CWE)
References
- https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8Patch
- https://github.com/protobufjs/protobuf.js/pull/2335Issue TrackingPatch
- https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5ProductRelease Notes
- https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-893MitigationVendor Advisory
FAQ
What is CVE-2026-59876?
CVE-2026-59876 is a vulnerability with a CVSS score of 4.8 (MEDIUM). protobufjs compiles protobuf definitions into JavaScript (JS) functions. From 8.2.0 until 8.6.5, the protobufjs Text Format extension parsed string-keyed map entries using ordinary property assignment...
How severe is CVE-2026-59876?
CVE-2026-59876 has been rated MEDIUM with a CVSS base score of 4.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-59876?
Check the references section above for vendor advisories and patch information. Affected products include: Protobufjs Project Protobufjs.