TLDR Tech / InfoSec
Microsoft confirms April Windows updates cause backup failures
Microsoft confirmed that April 2026 security updates added the psmounterex.sys kernel driver to the Vulnerable Driver Blocklist to mitigate CVE-2023-43896 (a high-severity buffer overflow enabling privilege escalation or arbitrary code execution), causing VSS snapshot timeouts and image-mount failures in Macrium Reflect, Acronis Cyber Protect Cloud, UrBackup Server, and NinjaOne Backup on Windows 10, 11, and Server.
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