kernel driver blocklist

The kernel driver blocklist tag covers Microsoft's practice of using Windows security updates to block vulnerable third-party kernel drivers. Recent threads focus on the April 2026 updates, including KB5083769 and KB5083631, which block the psmounterex.sys driver used by backup software for mounting disk images. This blocklist is part of Microsoft's effort to reduce the Windows attack surface by preventing outdated or vulnerable drivers from running in kernel mode. The tag includes discussions of operational impacts, such as backup restore and mount failures, as well as registry workarounds and the broader security implications for enterprise IT administrators. The kernel driver blocklist represents a shift in how Microsoft handles driver security, prioritizing system integrity over backward compatibility.