The disruptive update addressed 1,413 vulnerabilities across various enterprise products, surpassing the previous annual record of 1,261 common vulnerabilities and exposures established in 2020. Among the fixes is a patch for a Windows Shell zero-day (CVE-2026-96951) that is currently being used by attackers to bypass Mark of the Web defenses.
Tuesday, October 20, 2026
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Microsoft's Record Security Update Breaks Exchange Servers
Cybersecurity2 days ago
A recent software fix for Windows Server has halted mail flow on high-capacity Microsoft Exchange installations, causing web-based Outlook to crash and emails to accumulate. The outages stem from a configuration change in the October update that caps the RPC Endpoint Mapper at 512 concurrent lookups, a limit that busy servers frequently exceed during normal operation.
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