Security patch or self-inflicted DDoS? Microsoft update knocks out key enterprise functions – Computerworld

An October 2025 Microsoft Windows security update is wreaking havoc on enterprises, impacting multiple systems with bugs ranging from annoying to showstopper.

The update in KB5066835 was intended to strengthen Windows cryptography, by moving from the older Cryptographic Services Provider (CSP) to the more secure Key Storage Provider (KSP), but users may now be experiencing issues with authentication, websites, updates, and even use of mice and keyboards.

These and other known issues impact Windows versions designated for broad deployment, including Windows 10 (version 22H2), Windows 11 (versions 23H2, 24H2, and 25H2), and Windows Server (2012, 2016, 2022, and 2025 releases).