How to Enable or Disable Untrusted Font Blocking in Windows 11 Tired of worrying about sneaky malware gaining deep system access? The threat may be lurking in fonts stored outside your default Windows directory. This is why Windows 11 offers an essential security feature called Untrusted Font Blocking, which restricts unsafe fonts from loading through the Graphics Device Interface. Before we begin, be sure to subscribe to NinjaOne's IT Video Hub and our YouTube channel for more tech content like this. The Purpose of Untrusted Font Blocking This feature is an important mitigation option. Malicious actors can embed harmful code within external font files to exploit vulnerabilities and gain deep system access. By enabling Untrusted Font Blocking, you can stop these untrusted fonts from ever loading, effectively closing a significant security gap on your Windows 11 PC. Now let's dive into the two main configuration methods. Enabling/Disabling via Windows Group Policy The Group Policy Editor method is recommended for IT administrators managing multiple devices and is available on Pro, Enterprise, and Education editions. First, open the Run dialog box and type gpedit.msc. Navigate to Computer Configuration Administrative Templates, System, Mitigation Options. Double-click the Untrusted Font Blocking policy. Select Enabled to activate the feature. Under the Options dropdown, you have three choices: Block untrusted fonts and log events for full enforcement. Log events without blocking Audit Mode. Do not block untrusted fonts to disable the feature. To completely disable the policy, choose Not Configured or Disabled. Click Apply and OK, then restart your PC. Using Registry Keys for Font Blocking Control If you are a Windows Home user or prefer a manual configuration method, the Registry Editor is your alternative. Remember to create a backup before proceeding. First, open the Run dialog and type regedit. Navigate to the key: HKEY_LOCAL_MACHINE\SOFTWARE\Policies \Microsoft\Windows NT\MitigationOptions. You may need to create the Mitigation Options key. In the right pane, create a new String Value named MitigationOptions_FontBlocking. Note the intentional spelling. Double-click the value and enter one of these data settings: To enable blocking: 1000000000000 To enable audit mode: 3000000000000 To disable: Set the value to 2000000000000 or delete the String Value entirely. Finally, click OK, close the editor, and restart your computer to apply the changes. Critical Prerequisites and Error Mitigation Here are the critical prerequisites and considerations. Prerequisites: Always ensure you have Administrator privileges before starting. Restart Required: You should always restart your PC after modifying policy or registry settings for the changes to take effect. Audit Mode Check: Use Audit Mode logging without blocking to check for application compatibility issues before full enforcement. Log Monitoring: If using Audit Mode, monitor logs in the Event Viewer under Application and Service Logs > Microsoft > Windows > Win32k > Operational, looking for Event ID 260. Registry Caution: Be extremely cautious in the Registry. Editing the wrong key can cause instability. If issues arise, restore from your backup. Whether you manage a large network or just your home PC, controlling Untrusted Font Blocking is straightforward. Use the method best suited for your Windows 11 edition, and enjoy a significant increase in defense against external font vulnerabilities. For more information, check out our official blog post on How to Enable or Disable Untrusted Font Blocking in Windows 11 linked in the description below.