CVE-2026-59876: CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in protobufjs protobuf.js
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.
CVE-2026-59876: CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in protobufjs protobuf.js
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 v3.1
Score 4.8medium
Weaknesses
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-07T15:41:53.607Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4e73c2c9d9e3dbe36042d4
Added to database: 07/08/2026, 15:58:58 UTC
Last updated: 07/08/2026, 15:58:58 UTC
Views: 1
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