CVE-2026-59876
Last modified
CVE-2026-59876 is a medium-severity vulnerability rated 4.8/10 on the CVSS scale. 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. EPSS estimates a 0.22% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Protobufjs Project | Protobufjs | >= 8.2.0, < 8.6.5 |
References
- https://github.com/protobufjs/protobuf.js/pull/2335Issue Tracking, Patch
- https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5Product, Release Notes
- https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934Mitigation, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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