CVE-2026-59876
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…
Does this matter?
Lower severity and a low EPSS score (0.35%). Track it; it rarely justifies an emergency change on its own.
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 3.1
- 4.8 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
- EPSS
- 0.35% probability · 28th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-1321
- Affected
- protobufjs project/protobufjs
- Source
- security-advisories@github.com
References
- https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8Patch
- 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.