Winnow is a modular Windows 11 optimization and debloating toolkit. Because Winnow modifies Windows system configurations, security and OS stability are paramount.

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• Winnow uses Group Policy and registry configurations to disable telemetry, Copilot, Recall, and background services. It never deletes system binaries (explorer.exe, SearchHost.exe), ensuring cumulative Windows Updates and anti-cheat drivers (Vanguard, EAC, BattlEye, FACEIT) remain 100 percent operational.

• Re-elevation processes rigorously escape paths, script parameters, and user flags to prevent command injection via crafted folder names or CLI arguments.

• The orchestrator validates execution policy and unblocks only signed/validated PowerShell scripts without disabling system-wide execution restrictions.

• Integrated -Verify and -VerifyProfile audit modes allow administrators to inspect system state and verify drift with exit code 2 before applying changes.

• The administrator check stops the run before any runtime module loads. Versions before 3.4.0 printed the warning but continued into the apply pipeline, because exit inside a dot-sourced script does not terminate the caller. A non-elevated run could reach registry imports and scheduled task changes and fail partway through, leaving a partially applied system.

• A failed apply restores the registry backup taken before the run instead of leaving the system half-changed. Exit code 3 reports a clean rollback, 4 reports a rollback that itself failed and names the backup file for manual recovery.

• The single-file Winnow-Standalone.ps1 checks for administrator rights before it unpacks anything. If not elevated it relaunches itself through UAC and only then extracts, into a fresh directory whose ACL is locked to Administrators and SYSTEM with inheritance disabled. Earlier builds extracted as the standard user and self-elevated afterward, so the elevated run dot-sourced scripts from a directory the standard user still controlled. That local privilege-escalation path is closed.

• The optional update watchdog runs its payload as SYSTEM on a scheduled trigger. Its directory under %ProgramData%\Winnow carries a protected ACL (SYSTEM and Administrators full control, users read and execute, inheritance off) re-applied on every install, and the payload's SHA256 is recorded in an administrator-only HKLM\SOFTWARE\Winnow\Watchdog key. The payload verifies that hash before it enforces anything and fails closed if the check does not match, so a tampered payload does not run. Integrity failures and corrected drift are written to the Windows event log (source Winnow) for auditing. -VerifyWatchdog reports health read-only.

• The software installer passes each winget package id as a discrete argument rather than interpolating it into a single command line, so a crafted id cannot inject extra flags. The generated autounattend.xml XML-escapes every user-supplied value, including the embedded config path, so a legal path containing &, <, or > cannot break the unattend file.

• Per-user and Sysprep runs that mount another profile's registry hive force a garbage collection to release lingering .NET registry handles before reg unload, and retry once. Earlier builds could leave the hive mounted and only warn, which risked locking the profile.