VULNERABILITY INTELLIGENCE

CVE-2026-59876

CVSS score4.8 MEDIUM

EPSS probability0.35%

CISA KEVNot currently listed

Published2026-07-08

Last modified2026-10-25

CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

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.

Weakness classification

security-advisories@github.com: CWE-1321

Primary references

security-advisories@github.com — Patch
security-advisories@github.com — Issue Tracking, Patch
security-advisories@github.com — Product, Release Notes
security-advisories@github.com — Mitigation, Vendor Advisory