Prototype pollution in protobuf.js - CVE-2026-44292
Published: May 12, 2026
Vulnerability identifier: #VU131162
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-44292
CWE-ID: CWE-1321
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to modify the prototype chain of a message instance.
The vulnerability exists due to improperly controlled modification of object prototype attributes in generated message constructors when copying enumerable properties from an attacker-controlled plain object. A remote attacker can supply an object containing an own enumerable __proto__ property to modify the prototype chain of a message instance.
This is a per-instance prototype injection issue and does not affect Object.prototype or other global prototypes.
Affected software
protobuf.js
How to mitigate CVE-2026-44292
Install security update from vendor's website.
protobuf.js - addressed in versions 7.5.6, 8.0.2