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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 · 7d agoAdvisory in the wildCVE-2026-85880CVE-2026-81963CVE-2026-70352+27 CVEs1

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 · 7d agoAdvisory in the wildCVE-2026-81963CVE-2026-85880CVE-2026-69676+27 CVEs

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 · 1d agoAdvisory 3 sources1

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 · 7d agoAdvisory

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 · 7d agoAdvisory in the wild

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

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 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

Windows memory integrity switches on automatically for eligible devices in October 2026

Microsoft's Windows quality updates will automatically enable memory integrity and Virtualization-based Security on eligible devices starting October 2026.

Beginning in October 2026, Windows quality updates will automatically enable memory integrity on eligible devices and turn on Virtualization-based Security where it is not already running. Memory integrity restricts kernel-mode execution to trusted, signed code and drivers, blocking kernel compromise and rootkits. Microsoft said existing administrator decisions remain in effect, and readiness checks weigh hardware capability, compatibility, and performance. Memory integrity also underpins hotpatch updates that install without a reboot, so unprotected devices are excluded from that servicing model.

Help Net Security · 13d agoAdvisory

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 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 · 7d agoAdvisory in the wildCVE-2026-81963CVE-2026-858801

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 · 7d agoAdvisory in the wildCVE-2026-69805CVE-2026-58649CVE-2026-69806+27 CVEs1

ZDI-26-619: Microsoft Windows UMPDDrvStretchBltROP Improper Object Management Local Privilege Escalation Vulnerability

ZDI disclosed CVE-2026-62712, a CVSS 7.8 improper object management flaw in Windows UMPDDrvStretchBltROP enabling local privilege escalation from low-privileged code.

The Zero Day Initiative published ZDI-26-619 covering a local privilege escalation vulnerability in Microsoft Windows' UMPDDrvStretchBltROP function, stemming from improper object management. Exploitation requires that the attacker first obtain the ability to run low-privileged code on the target system. ZDI rated the issue CVSS 7.8 and assigned CVE-2026-62712, the same identifier listed in the companion UMPDDrvRealizeBrush advisory.

ZDI Published Advisories · 8d agoAdvisory 4 sourcesCVE-2026-627121

ZDI-26-622: Microsoft Windows IKEv2 AES-GCM Decryption Integer Underflow Remote Code Execution Vulnerability

ZDI disclosed CVE-2026-50696, a CVSS 8.1 integer underflow in Windows IKEv2 AES-GCM decryption enabling unauthenticated remote code execution on specific IPsec configurations.

The Zero Day Initiative published ZDI-26-622 describing a remote code execution vulnerability in Microsoft Windows' IKEv2 AES-GCM decryption path, caused by an integer underflow. Authentication is not required for exploitation, but only systems using specific IPsec configurations are affected. ZDI assigned the vulnerability a CVSS score of 8.1 and the identifier CVE-2026-50696.

ZDI Published Advisories · 8d agoAdvisoryCVE-2026-506961

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

ZDI-26-539: (Pwn2Own) Microsoft Windows ipt.sys Incorrect Permission Assignment Local Privilege Escalation Vulnerability

ZDI advisory discloses Windows ipt.sys local privilege escalation (CVE-2026-65773, CVSS 7.8) demonstrated at Pwn2Own.

ZDI advisory ZDI-26-539 describes an incorrect permission assignment flaw in Microsoft Windows ipt.sys, tracked as CVE-2026-65773 with a CVSS score of 7.8. A local attacker who can already execute low-privileged code can exploit it to escalate privileges. The vulnerability was demonstrated at Pwn2Own.

ZDI Published Advisories · Aug 11, 2026AdvisoryCVE-2026-657731

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 confirms KB5002914 Excel update breaks copy and paste

Microsoft confirms KB5002914 Office security update silently breaks copy-paste, autofill, and formula dragging in Excel 2016 through 2024.

Microsoft confirmed the September 2026 KB5002914 security update breaks copy-and-paste, autofill, and formula dragging in Excel 2024, 2021, 2019, and 2016. Failures occur silently with no beep or error message, leaving the destination unmodified. Uninstalling KB5002914 via OfficeC2RClient or Oarpmany restores functionality while Microsoft investigates.

BleepingComputerupdated · 1d agofirst · 1d agoAdvisory 3 sources1

Best Practices for Good Endpoint Hardening | Huntress

Huntress outlines endpoint hardening best practices, citing exposed RDP, RMM tool abuse, and ClickFix social engineering as common SMB intrusion paths.

Huntress published defensive guidance on endpoint hardening for small and mid-sized businesses, drawing on observations from its SOC. The post describes common intrusion vectors: internet-exposed RDP brute-forced by automated scanners, phishing emails delivering attacker-controlled remote monitoring and management (RMM) tools, with Huntress reporting a 277% spike in RMM abuse in 2025, and ClickFix attacks using fake CAPTCHA pages that trick users into running malicious commands. Recommended controls include scanning for exposed RDP, SSH, and VPN interfaces, removing unneeded local admin rights, enabling Windows Defender tamper protection, disabling SMBv1, and standardizing on one approved remote access tool, guided by CIS and NIST frameworks.

Huntress · 6d agoAdvisory

CISA tells operators to harden Siemens S7 PLCs. Here’s how to do it without disrupting production

CISA, NSA, FBI and other agencies warn of active targeting of internet-exposed Siemens S7 PLCs and urge patching, exposure removal and hardening.

Joint advisory AA26-231A from the NSA, CISA, FBI, Department of Energy and EPA warns that actors are actively targeting Siemens S7 PLCs using internet scanning, AI-assisted scripts and libraries such as Snap7 and python-snap7 over S7comm on TCP port 102. The advisory covers S7-200 through S7-1500 series controllers and recommends patching, removing internet exposure, access controls, monitoring and disabling unneeded services. Siemens states no new S7 vulnerabilities are involved, only misconfigurations addressed in existing ProductCERT guidance SSB-104599. The article details how to apply each measure without breaking production dependencies such as remote I/O, HMI links and diagnostics.

CSO Online · 7d agoAdvisory in the wild

Arbitrary process termination from exposed minifilter communication port

Fortinet FortiClient Windows fortimon3 driver flaw (CVSS 4.7) lets authenticated attackers terminate arbitrary processes via exposed minifilter communication port.

Fortinet advisory FG-IR-26-165 discloses an unverified ownership vulnerability (CWE-283, CVSSv3 4.7) in the FortiClient Windows fortimon3 minifilter driver. An authenticated attacker can terminate arbitrary processes through an exposed minifilter communication port. The advisory was revised on 2026-09-08.

Fortinet PSIRT · 8d 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 · 19d agoAdvisory1