Patch Tuesday - September 2026
Microsoft's September 2026 Patch Tuesday fixes 999 CVEs, a record, with two zero-day privilege escalation flaws already exploited in the wild.
Permissive Cross-Domain Policy Privilege Elevation in Microsoft Azure Arc
Microsoft Azure Arc (CVE-2026-62895) contains a privilege elevation flaw caused by a permissive cross-domain policy that trusts untrusted domains, mapped by Microsoft to CWE-942 (permissive cross-domain policy with untrusted domains), CWE-1390 (weak authentication) and CWE-89 (SQL injection). An unauthenticated attacker can exploit it over a network, with CVSS scoring indicating some user interaction is required (AV:N/AC:L/PR:N/UI:R), by abusing the overly permissive cross-domain trust to elevate privileges, with high impact on confidentiality, integrity and availability (CVSS 3.1: 8.8 High). Any organization using Azure Arc to manage hybrid or multi-cloud resources is potentially affected. There is no evidence of exploitation in the wild, no known public proof-of-concept, the flaw is not in CISA's KEV catalog, and EPSS estimates only a 0.7% probability of exploitation in the next 30 days (52nd percentile). Microsoft addressed the flaw as part of its September 2026 Patch Tuesday release, which fixed 966 flaws including 2 zero-days.
What to do: Apply Microsoft's September 2026 Patch Tuesday updates for Azure Arc across all Arc-enabled infrastructure, prioritizing environments where unauthenticated network users can reach Arc-connected resources. The available data does not include fixed version or KB details, so consult the Microsoft advisory for CVE-2026-62895 to identify the patched build for your components. In the interim, review and tighten the domains Azure Arc trusts in cross-domain policies and treat any unauthenticated network access to Arc-managed resources as a privilege-elevation risk.
| Product | Affected |
|---|---|
| Microsoft Azure Arc | — |
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Permissive cross-domain policy with untrusted domains in Azure Arc allows an unauthorized attacker to elevate privileges over a network.
Microsoft's September 2026 Patch Tuesday fixes 999 CVEs, a record, with two zero-day privilege escalation flaws already exploited in the wild.
Microsoft's September 2026 Patch Tuesday fixes a record 966 flaws, including two Windows zero-days actively exploited to gain SYSTEM privileges.
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