Elevated Privilege via Incorrect Use of Privileged APIs in Unity Parsec on Windows

An Incorrect Use of Privileged APIs vulnerability in Unity Parsec on Windows hosts leads to a potential Elevation of Privilege. This issue affects Parsec through v2026-05-04.0. The patched version is Parsec for Windows version 150-104a. A user can generate a situation where there is an instance of parsecd.exe running as NT AUTHORITY\SYSTEM with a user-controlled value of the AppData environment variable.

Unity Parsec has a TOCTOU race condition that permits local attackers to escalate privileges to SYSTEM if Parsec was installed in "Per User" mode. The application intentionally launches DLLs from a user-owned directory but intended to always perform integrity verification of those DLLs. This affects Parsec Loader versions through 8. Parsec Loader 9 is a fixed version.