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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.

GBHackers · 7d agoAdvisory in the wildCVE-2026-85880CVE-2026-85877CVE-2026-85875+27 CVEs1

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.

Zero Day Initiative Blog · 8d agoAdvisory in the wildCVE-2026-85880CVE-2026-81963CVE-2026-70352+27 CVEs1

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.

Canadian Centre for Cyber Security · 8d agoAdvisory in the wildCVE-2026-81963CVE-2026-858801

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.

Cisco Talos · 8d agoAdvisory in the wildCVE-2026-81963CVE-2026-85880CVE-2026-69676+27 CVEs

Microsoft September 2026 Patch Tuesday fixes 966 flaws, 2 zero-days

Microsoft's September 2026 Patch Tuesday fixes a record 966 flaws, including two Windows zero-days actively exploited to gain SYSTEM privileges.

Microsoft's September 2026 Patch Tuesday addresses a record 966 vulnerabilities, including 105 rated Critical, 81 of them remote code execution bugs. Two zero-days were actively exploited: a Windows Update Stack link-following flaw and a Windows ALPC heap-based buffer overflow, both allowing local elevation to SYSTEM privileges. The ALPC flaw was reported by Volexity and Proofpoint researchers, while the Update Stack flaw was credited to Romain Deperne and the Microsoft Threat Intelligence Centre. Microsoft shared no details on how the flaws were exploited in attacks.

BleepingComputer · 8d agoAdvisory in the wildCVE-2026-69805CVE-2026-58649CVE-2026-69806+27 CVEs1

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.

Cyber Security News · 1d agoAdvisory 3 sourcesCVE-2026-81399CVE-2026-81390CVE-2026-819541

Microsoft Confirms Remote Desktop Services Might Stop Working Following Sept. 2026 Security Update

Microsoft's September 2026 Patch Tuesday updates (KB5124008) can break Remote Desktop Services, causing RDP failures and freezes across Windows clients and servers.

Microsoft confirmed its September 2026 security updates, including KB5124008 for Windows 11 24H2/25H2, introduced a reliability regression where RDP connections fail after several minutes and servers hang at the 'Please wait for the Remote Desktop Configuration' screen. MMC, RDS Licensing Diagnoser, File Explorer, and the Windows Update settings page may also stop responding. The issue affects Windows 10/11 clients and Windows Server 2012 through 2025; Microsoft marked it Mitigated on September 11 and is developing a permanent fix, with VM restart offered as a temporary workaround.

Cyber Security News · 2d agoAdvisory

Microsoft releases emergency Windows updates to fix RDS failures

Microsoft released emergency out-of-band Windows updates fixing Remote Desktop Services failures and Hyper-V issues caused by September 2026 security patches.

Microsoft issued out-of-band updates on September 14, 2026 to fix Remote Desktop Services instability introduced by the September security updates, which caused RDP connection and sign-in failures and unresponsive servers. Updates include KB5129194 (Windows 11 26H1), KB5129195 (Windows 11 24H2/25H2), KB5129236 (Windows 10), KB5129235 (Windows Server 2025), and KB5129237 (Windows Server 2022). The Windows 11 updates also fix a Hyper-V Plan9 shared folder issue and some USB Audio Class 1.0 multichannel problems, though remaining USB audio issues await a fix. Admins had previously used Group Policy mitigations or uninstalled the security updates, which removed security protections.

BleepingComputerupdated · 1d agofirst · 2d agoAdvisory 3 sources1

Microsoft Patch Tuesday for August 2026 Fixed a Zero

Microsoft's August 2026 Patch Tuesday fixes 398 CVEs, including an actively exploited WinSock zero-day CVE-2026-68820 and wormable DNS RCE CVE-2026-62878.

Microsoft's August 2026 Patch Tuesday addresses 398 CVEs across Windows, Office, Azure, Exchange Server, SharePoint, Teams, .NET and other products, with 62 rated Critical. The actively exploited CVE-2026-68820 is a use-after-free in the Windows WinSock afd.sys driver that can yield SYSTEM privileges via a race condition. CVE-2026-62878 is a critical, wormable stack buffer overflow in Windows DNS Server allowing unauthenticated, remote code execution without user interaction. Other notable fixes include WDS TFTP RCE CVE-2026-62893, a QUIC flaw affecting roughly 13.5 million sites (CVE-2026-62815), an Exchange authentication bypass EoP demonstrated at Pwn2Own Berlin (CVE-2026-62911), and two TPM 2.0 reference implementation fixes.

Security Affairs · Aug 12, 2026Advisory in the wildCVE-2026-68820CVE-2026-62878CVE-2026-62893+5 CVEs

Microsoft: Windows Server 2025 changes causing app crashes

Microsoft warns Windows Server 2025 memory-management changes crash AWE apps, including SQL Server with Lock Pages in Memory; disable LPIM as workaround.

Microsoft confirmed a known issue where Windows Server 2025 memory-management changes cause access violations, memory corruption, or unexpected termination in applications using Address Windowing Extensions (AWE). SQL Server running with the Lock Pages in Memory (LPIM) policy is affected, with symptoms including 0xC0000005 access violations, DBCC CHECKDB failures, crash dumps, and services stopping or restarting unexpectedly. Microsoft's temporary workaround is to disable the LPIM policy for the SQL Server service account or disable AWE in other affected apps, with a permanent fix promised in a future Windows update.

BleepingComputer · 8d agoAdvisory1

September 2026 Patch Tuesday: Record patch count, 2 zero-days, and a SigRed successor

Microsoft's September 2026 Patch Tuesday delivers a record patch count, fixing two exploited zero-days and a wormable DNS flaw dubbed a SigRed successor.

Microsoft's September 2026 Patch Tuesday sets another record patch count, fixing two vulnerabilities exploited as zero-days: CVE-2026-81963, a Windows Update Stack low-privilege-to-SYSTEM escalation reported by MSTIC, and CVE-2026-85880, a Windows Advanced Local Procedure Call escalation reported by Proofpoint. Zero Day Initiative's Dustin Childs urges priority on a cluster of 20 potentially wormable bugs including DNS RCE CVE-2026-69730, described as a spiritual successor to SigRed, plus Kerberos authentication bypass CVE-2026-69676 that could give any authenticated domain user RCE on domain controllers, and Exchange RCE CVE-2026-55007 via a malicious Visio attachment. All Windows fixes are bundled in cumulative updates, and experts stress prioritizing exploitable, reachable flaws over raw patch counts.

Help Net Security · 7d agoAdvisory in the wildCVE-2026-81963CVE-2026-85880CVE-2026-69730+4 CVEs

Microsoft releases Windows 10 KB5122878 extended security update

Microsoft shipped Windows 10 ESU update KB5122878, delivering the record September 2026 Patch Tuesday fixes, including patches for two actively exploited zero-days.

Microsoft released KB5122878 for Windows 10 Enterprise LTSC and ESU customers, moving builds 19045/19044 to .7725 with security and bug fixes. The update carries this month's record September 2026 Patch Tuesday set, which fixed 966 Microsoft vulnerabilities including two actively exploited zero-day flaws. It also fixes BitLocker recovery-key prompts and Remote Desktop audio redirection, and updates Secure Boot certificate rollout and Morocco time zone data. Microsoft reports no known issues with the update.

BleepingComputer · 8d agoAdvisory in the wild

Windows 11 cumulative updates KB5124008 & KB5122880 released

Microsoft shipped mandatory September 2026 Patch Tuesday cumulative updates KB5124008 and KB5122880 for Windows 11, fixing vulnerabilities and adding features.

Microsoft released Windows 11 KB5124008 (versions 25H2/24H2) and KB5122880 (23H2) cumulative updates containing the September 2026 Patch Tuesday security patches, described as covering 1,000 vulnerabilities discovered in previous months. The updates are mandatory and add features including movable and resizable taskbars, Start menu customization, a Windows Search option to hide Bing and Store web suggestions, and Administrator Protection, a just-in-time admin privilege feature that is off by default and configurable via Intune OMA-URI or Group Policy.

BleepingComputer · 8d agoAdvisory

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.

CSO Online · 5d agoAdvisory

August updates trigger 0xc0000409 errors on Windows Server 2016

Microsoft says the August 2026 security update causes recurring CompatTelRunner.exe 0xc0000409 crashes on Windows Server 2016 with Compatibility Appraiser enabled; no functional impact.

Microsoft confirmed a known issue in which the August 2026 Windows security update generates recurring Application Error events (Event ID 1000, exception code 0xc0000409) in CompatTelRunner.exe on Windows Server 2016. The issue affects physical and virtual machines, including VMware and Azure environments, and per Microsoft does not affect device functionality. A permanent fix is planned for a future update, and the event log entries can be dismissed temporarily.

BleepingComputer · 8d agoAdvisory

Microsoft Patch Tuesday for August 2026 — Snort rules and prominent vulnerabilities

Microsoft's August 2026 Patch Tuesday fixes 421 vulnerabilities across its products, including 62 rated critical; Cisco Talos published analysis and matching Snort rules.

Microsoft released its August 2026 monthly security update addressing 421 vulnerabilities across a range of products. Of these, 62 flaws were rated critical by Microsoft. Cisco Talos highlighted the most prominent vulnerabilities in the release and published Snort rules for detection of related exploitation attempts.

Cisco Talos · Aug 11, 2026Advisory

ZDI-26-629: Microsoft Azure Entra ID OAuth Device Code Grant Information Disclosure Vulnerability

Zero Day Initiative disclosed an unauthenticated information disclosure vulnerability (CVSS 5.8) in Microsoft Azure Entra ID's OAuth device code grant flow.

ZDI published advisory ZDI-26-629 describing an information disclosure vulnerability in Microsoft Azure Entra ID related to the OAuth device code grant. Remote attackers can disclose sensitive information without authentication. ZDI assigned a CVSS 3.1 score of 5.8; no CVE identifier is listed in the advisory text.

ZDI Published Advisories · 7d agoAdvisory1

Microsoft security advisory – August 2026 monthly rollup (AV26-804) – Update 2

Canada's Cyber Centre updated advisory AV26-804 relaying Microsoft's August 2026 monthly rollup of vulnerabilities across .NET and Azure products.

The Canadian Centre for Cyber Security advisory AV26-804, updated August 27, 2026, relays Microsoft's August 2026 monthly security rollup originally issued August 11. Affected products include .NET 8.0, 9.0, and 10.0 on Linux, macOS, and Windows, plus many Azure services. Listed Azure components include Azure Kubernetes Service, Azure SQL Database, Azure Service Bus, Azure Active Directory, Azure Logic Apps, and Azure Monitor Agent.

Canadian Centre for Cyber Security · 20d agoAdvisory1

ZDI-26-605: Microsoft Windows Localized Filenames Improper Input Validation NTLM Response Information Disclosure Vulnerability

ZDI advisory ZDI-26-605 details an improper input validation flaw (CVE-2026-50508, CVSS 3.3) in Microsoft Windows localized filenames that leaks NTLM responses.

The Zero Day Initiative released advisory ZDI-26-605 describing improper input validation in Microsoft Windows handling of localized filenames. Remote attackers can disclose NTLM authentication responses if the target opens a malicious file or visits a crafted page. ZDI rated the issue CVSS 3.3 and assigned CVE-2026-50508. Leaked NTLM responses could enable offline credential cracking.

ZDI Published Advisories · 23d agoAdvisoryCVE-2026-505081

Microsoft Fixes 400 Flaws on August Patch Tuesday

Microsoft's August Patch Tuesday delivers fixes for 400 security vulnerabilities across its product lineup.

Microsoft released its August Patch Tuesday security updates, fixing 400 vulnerabilities, described as another massive monthly batch. The source text provides no breakdown of severity classes, affected products, or whether any flaws were actively exploited. Defenders should prioritize patching based on Microsoft's exploitation status ratings in the official bulletin.

Infosecurity Magazine · Aug 12, 2026Advisory

ZDI-26-535: (Pwn2Own) Microsoft Exchange External Control of File Path Remote Code Execution Vulnerability

ZDI advisory discloses Microsoft Exchange remote code execution flaw (CVE-2026-62911, CVSS 7.2) with bypassable authentication.

ZDI advisory ZDI-26-535 describes an external control of file path vulnerability in Microsoft Exchange, tracked as CVE-2026-62911 with a CVSS score of 7.2. Remote attackers can execute arbitrary code on affected installations. Although authentication is required, the existing authentication mechanism can be bypassed.

ZDI Published Advisories · Aug 11, 2026AdvisoryCVE-2026-62911