CVE-2026-44291: Protobufjs Project Protobufjs

High severity, CVSS 8.1. EPSS: 0.4% chance of exploitation in the next 30 days.

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If Object.prototype had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information. This could cause attacker-controlled strings to be emitted into generated JavaScript code. This vulnerability is fixed in 7.5.6 and 8.0.2.

Affected products

• Protobufjs Project Protobufjs: before 7.5.6 (fixed in 7.5.6); from 8.0.0, before 8.0.2 (fixed in 8.0.2)

Published 2026-05-13. Last modified 2026-06-17.