toctou hardening

The toctou hardening tag covers a focused WSL security fix in Microsoft’s WSL 2.7.10 servicing update. The change addresses how persisted virtual hard disk mounts are restored after the WSL utility virtual machine is recreated. During recovery, WSL now passes the mounting user’s token when restoring a VHD, helping prevent a user-controlled path from being re-resolved with SYSTEM privileges. This work strengthens a security boundary between ordinary users and elevated system processes, particularly when persisted VHD paths are involved. The tagged content is narrowly centered on Windows Subsystem for Linux, VHD restoration behavior, token handling, and preventing time-of-check to time-of-use path resolution issues.