Patch Tuesday notes: Microsoft fixes three zero-days.

Microsoft's Patch Tuesday addressed 421 vulnerabilities including three zero-days — one an actively exploited Windows Ancillary Function Driver for WinSock privilege escalation now on CISA's Known Exploited Vulnerabilities list and attributed by Check Point to North Korea's Lazarus Group — while a critical SharePoint authentication-bypass (CVE-2026-55040) published with a PoC is already being weaponized; the bulletin also notes fixes from Adobe, SAP and ICS vendors and briefly covers Visa and Deel acquiring identity verification firms.