CVE-2026-59876

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 4.8 MEDIUM

4.8^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 2.5

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8
https://github.com/protobufjs/protobuf.js/pull/2335
https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5
https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934

Configurations

No configuration.

History

08 Jul 2026, 16:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-08 16:16

Updated : 2026-07-09 16:16

NVD link : CVE-2026-59876

Mitre link : CVE-2026-59876

CVE.ORG link : CVE-2026-59876

JSON object : View

Products Affected

No product.

CWE

CWE-1321

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

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