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Microsoft security advisory – September 2026 monthly rollup (AV26-896) – Update 1
Canada's Cyber Centre relays Microsoft's September 2026 rollup; CISA added exploited zero-days CVE-2026-85880 and CVE-2026-81963 to KEV.
Advisory AV26-896 from the Canadian Centre for Cyber Security summarizes Microsoft's September 2026 monthly security rollup, listing affected products across Windows, Office, .NET, Azure, Exchange and SQL Server. It notes Microsoft confirmed CVE-2026-81963 and CVE-2026-85880 have been exploited. On September 8, 2026, CISA added both CVEs to its Known Exploited Vulnerabilities catalog, and administrators are urged to apply the updates.
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Update your firewall rules: Teams and Copilot are changing address
Microsoft is redirecting Microsoft 365 and Teams web users to new *.cloud.microsoft domains, requiring firewall and proxy rule updates by early October.
Starting September 2026, Microsoft is redirecting M365 web users to copilot.cloud.microsoft and Teams web users to teams.cloud.microsoft, announced via MessageCenter posts MC1465764 and MC1462915. All redirects should complete by early October 2026, with limited Teams exceptions possible until December 31, 2026. Microsoft advises reviewing client, proxy, firewall, and secure web gateway configurations, and suggests using TenantRestrictions to control personal Microsoft account access instead of blocking the new Copilot address.
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CISA Shares 17 Techniques Used by Hackers to Compromise Active Directory
CISA and five international agencies publish joint guidance detailing 17 techniques attackers use to compromise Microsoft Active Directory environments.
CISA, NSA, and the Australian Signals Directorate's ACSC, with contributions from Canadian, UK, and New Zealand cyber centers, released technical guidance on 17 Active Directory attack techniques. It covers AD Domain Services, AD Certificate Services, and AD Federation Services, including Kerberoasting, DCSync, Golden Ticket, Golden SAML, Skeleton Key, and Shadow Credentials. The guidance recommends treating domain controllers, CAs, AD FS servers, and Entra Connect systems as Tier 0 assets with phishing-resistant MFA, Kerberos pre-authentication enforcement, and disabling NTLM/SMBv1.
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Microsoft Confirms KB5002914 Update Breaks Copy and Paste on Excel
Microsoft confirms KB5002914 Excel security update silently breaks copy-paste in Excel 2016-2024, forcing admins to choose between usability and security fixes.
Microsoft added a known issue to KB5002914, the September 8, 2026 Excel security update, where paste, autofill, and formula dragging fail silently with no error in Excel 2016, 2019, 2021, and 2024. The update addresses remote code execution and information disclosure flaws including CVE-2026-81399, CVE-2026-81390, and CVE-2026-81954. No hotfix date has been published as of September 15, 2026; the only widely confirmed recovery is uninstalling or rolling back KB5002914, which drops the month's Excel security fixes.
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The September 2026 Security Update Review
ZDI's September 2026 Microsoft update review lists two already-exploited Windows EoP zero-days and dozens of critical RCEs across Office, SQL Server, and Windows services.
The review catalogs Microsoft's September 2026 fixes, marking CVE-2026-85880 (Windows ALPC) and CVE-2026-81963 (Windows Update Stack) as already exploited elevation-of-privilege issues. It also lists critical RCE flaws in Office, Word, Excel, PowerPoint, Outlook, SQL Server, Windows DNS, DHCP and Failover Cluster, plus graphics component RCEs. Azure-side fixes include Entra ID, Copilot Studio, Azure AI Language and Azure AD B2C elevation-of-privilege flaws.
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Kaspersky Security Bulletin 2020
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Microsoft September 2026 Patch Tuesday Fixes 973 Vulnerabilities and 2 Exploited Zero-Days
Microsoft's September 2026 Patch Tuesday fixes 973 vulnerabilities, including two zero-days already exploited in the wild.
Microsoft's September 2026 Patch Tuesday addresses 973 vulnerabilities across Windows, Office, and Azure components, including two zero-days already exploited in the wild. CVE-2026-81963, an elevation of privilege flaw in the Windows Update Stack, is flagged as an exploited zero-day. The release includes numerous remote code execution and information disclosure fixes for Microsoft Excel and Word, plus patches for the Windows kernel, ALPC, Print Spooler, ReFS, Entra ID, and Azure CLI.
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Microsoft Patch Tuesday for September 2026 — Snort rules and prominent vulnerabilities
Microsoft's September 2026 Patch Tuesday fixes 973 vulnerabilities, including 113 critical, with two Windows privilege-escalation bugs (CVE-2026-81963, CVE-2026-85880) exploited in the wild.
Microsoft's September 2026 security update addresses 973 vulnerabilities across its product lineup, 113 rated critical, of which 82 are remote code execution flaws. Two vulnerabilities are confirmed exploited in the wild: CVE-2026-81963, an elevation-of-privilege flaw in the Windows Update Stack (CVSS 7.8), and CVE-2026-85880, a heap-based buffer overflow in Windows Advanced Local Procedure Call (CVSS 7.8). Microsoft flags several bugs as more likely to be exploited, including a 9.8 RCE in Windows DNS Server (CVE-2026-69730), an 8.8 RCE in Windows Kerberos (CVE-2026-69676), and a 9.0 EoP in Spring Cloud Azure (CVE-2026-69854). Cisco Talos published accompanying Snort rules to detect exploitation attempts against the prominent flaws.
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