Microsoft Azure AI Foundry CVSS 10.0 Authentication Bypass CVE-2026-85889 and Windows Zero-Day Exploitation
During Microsoft's September 2026 Patch Tuesday, a critical CVSS 10.0 authentication bypass (CVE-2026-85889) was disclosed in the Azure AI Foundry internal management API. This vulnerability allowed unauthenticated network attackers to invoke privileged functions, enabling immediate administrator role escalation. A subsequent chain of five vulnerabilities (CVE-2026-85890 through CVE-2026-85894) facilitated cross-tenant access, session hijacking, and arbitrary code execution within the Foundry sandbox. Concurrently, two Windows zero-day vulnerabilities in win32k.sys (CWE-416) and spoolsv.exe (CWE-120) were observed being actively exploited in the wild for approximately 72 hours before out-of-band patches were released. While the Azure vulnerability was mitigated server-side, immediate client-side patching is required for all Windows systems to prevent kernel-mode exploitation.