Microsoft's Patch Tuesday on September 8, 2026, addressed two critical Windows privilege escalation vulnerabilities: CVE-2026-85880 and CVE-2026-81963, both with a CVSS score of 7.8. CVE-2026-85880 is a heap-based buffer overflow in the Windows Advanced Local Procedure Call (ALPC), allowing attackers with low-privilege local access to escalate privileges to SYSTEM. CVE-2026-81963 involves improper link resolution in the Windows Update Stack, enabling similar privilege escalation. Both vulnerabilities require no user interaction and have been actively exploited prior to the patch release. CISA added them to its Known Exploited Vulnerabilities catalog on September 8, 2026, with a remediation deadline of September 22 for U.S. federal agencies.
CVE-2026-85880 affects various Windows 10 and Server versions but excludes Windows 11 and Windows Server 2025. CVE-2026-81963 impacts newer Windows platforms, including Windows 11 and Windows Server 2025. Microsoft released security updates for both vulnerabilities on September 8, 2026, and organizations are advised to prioritize these updates. Security teams should monitor for signs of privilege escalation and unusual SYSTEM-level activities related to these vulnerabilities.