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Windows 11 Security Update KB5124008 Breaks Always-On VPN Connections
Microsoft's September 2026 Windows 11 update KB5124008 breaks certificate-based Always On VPN on some enterprise clients, forcing admins to pause rollout.
Microsoft's September 8, 2026 cumulative update KB5124008 for Windows 11 24H2 (build 26100.9445) and 25H2 (build 26200.9445) breaks certificate-based Always On VPN tunnels on some enterprise clients, with connectivity restored after uninstalling the update and rebooting. The issue was first detailed on Microsoft Q&A on September 9 by an administrator using Intune-deployed VPN profiles with RRAS and NPS on Windows Server 2019. The same mandatory Patch Tuesday package fixes two actively exploited zero-days, CVE-2026-81963 in the Windows Update Stack and CVE-2026-85880 in Windows Advanced Local Procedure Call, so many teams are pausing only VPN cohorts rather than blocking the full rollout.
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Researchers Turn USB Auto-Install Into a Full SYSTEM Takeover on Windows 11
DEF CON researchers chained Windows Plug and Play auto-install abuse with third-party driver flaws to reach SYSTEM on fully updated Windows 11.
In 'Plug And Pwn' research prepared for DEF CON 34, Alejandro Hernando and Borja Martinez emulated USB devices so Windows auto-installed signed vendor software, chaining a Sierra Wireless SwiService.exe SetDNS primitive, a Sony FeliCa co-installer path-traversal flaw that writes a DLL into System32, and device reconnection for SYSTEM code execution. A remote variant over Remote Desktop forges a synthetic Intel RealSense device and abuses a CRYPTBASE.dll search-order hijack when PnP or low-level USB redirection is enabled. Microsoft notes RDP does not allow supported PnP and RemoteFX USB redirection by default, and no in-the-wild exploitation has been reported.
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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.
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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.
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August 2026 Patch Tuesday forecast: How do we deal with the patch apocalypse?
August 2026 Patch Tuesday forecast urges risk-based triage as AI inflates CVE volume, flags actively exploited SharePoint RCE CVE-2026-50522 and LegacyHive Windows flaw.
July 2026 Patch Tuesday set records with over 600 CVEs, including 405 for Windows 11 and Server 2025, though only two were exploited zero-days and one was publicly disclosed. The author recommends prioritizing known-exploited and internet-facing vulnerabilities, matching patches to high-risk systems, and accelerating ring-based deployment toward Microsoft's suggested three-day turnaround. Notable items include actively exploited SharePoint RCE CVE-2026-50522 enabling machine key theft, the unassigned LegacyHive Windows User Profile Service flaw, and several end-of-servicing dates for Windows and Exchange.
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Windows BitLocker Vulnerability Allows Attackers to Execute Malicious Code Remotely
Microsoft patched CVE-2026-69449, a heap-based buffer overflow in Windows BitLocker enabling code execution, affecting Windows 10/11 and Server 2012-2025 in September 2026 updates.
Microsoft disclosed CVE-2026-69449, a heap-based buffer overflow in Windows BitLocker rated Important, which could allow an authorized attacker to execute arbitrary code locally, with possible in-network exploitation via arbitrary endpoint calls. Microsoft rates exploitation as Less Likely and there was no public disclosure or in-the-wild exploitation at release. The flaw affects Windows 10 (1607-22H2), Windows 11 (23H2-26H1), and Windows Server 2012 through 2025, including Server Core. Fixes shipped in the September 2026 Patch Tuesday cumulative updates via platform-specific KBs such as KB5124012 and KB5122871.
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ShieldBreak: New Windows Zero-Day Bypasses Microsoft’s RoguePlanet Patch
Researcher Chaotic Eclipse published a PoC bypassing Microsoft's CVE-2026-50656 Defender patch, enabling SYSTEM-level code execution on fully patched Windows systems.
Security researcher Chaotic Eclipse released a proof-of-concept for ShieldBreak, a Microsoft Defender zero-day that fully bypasses the patch for CVE-2026-50656 (RoguePlanet), a race condition in the Malware Protection Engine (mpengine.dll) allowing SYSTEM-level code execution. The PoC was tested on Windows 11 25H2 and Windows Server 2025 with a 100% success rate, and Windows 10 is also vulnerable though not supported by the PoC; the flaw may also leak 8 bytes of memory. Microsoft's MSRC had criticized the researcher's repeated uncoordinated disclosures, including YellowKey (BitLocker bypass), GreenPlasma, and LegacyHive (User Profile Service LPE).
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ShieldBreak Zero-Day PoC Claims Microsoft Defender Patch Bypass With SYSTEM Access
Researcher Chaotic Eclipse released ShieldBreak PoC, a claimed patch bypass for Microsoft Defender flaw CVE-2026-50656, now tracked as CVE-2026-69414.
Researcher Chaotic Eclipse released a PoC for ShieldBreak, a claimed full patch bypass of Microsoft Defender flaw CVE-2026-50656 (RoguePlanet), which can yield SYSTEM privileges. Independent researchers Kevin Beaumont and Will Dormann validated the exploit on Windows 11 25H2 and Windows Server 2025, noting it requires Defender to be enabled. Microsoft assigned CVE-2026-69414 (CVSS 7.8) with an 'Exploitation More Likely' assessment and is investigating, but has not yet released a patch. The article also notes CISA's KEV addition of the actively exploited Windows AFD.sys flaw CVE-2026-68820.
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Chaotic Eclipse Releases Kaspersky Zero
Researcher Chaotic Eclipse released HardBreacher, a PoC privilege-escalation exploit for Kaspersky Endpoint Security on fully patched Windows 11 25H2.
Security researcher Chaotic Eclipse, also known as INFINITE NIGHTMARE and Nightmare-Eclipse, released a PoC zero-day exploit named HardBreacher targeting Kaspersky Endpoint Security v14.0.0.504. The exploit achieves privilege escalation on fully patched Windows 11 25H2, creating a DLL in System32 with full user permissions and potentially disrupting Kaspersky's UI process and file-access controls. The PoC is unstable and may require repeated attempts; Kaspersky claims it has already addressed the vulnerability.
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Prolific Microsoft 0-day hunter drops CrowdStrike Falcon exploit PoC
Researcher Nightmare Eclipse released a PoC for FalconFlank, a privilege escalation zero-day in CrowdStrike Falcon's Office macro remediation feature.
Researcher Nightmare Eclipse published a zero-day PoC dubbed FalconFlank targeting CrowdStrike Falcon's Microsoft Office malicious macro removal feature, achieving privilege escalation on fully updated Windows 11 25H2 and Windows Server 2025 with Optimal Protection and macro removal enabled. Kevin Beaumont independently confirmed the exploit works. The same researcher also released HardBreacher, an elevation-of-privilege bug in Kaspersky Endpoint (since fixed via update), PrettyPrague, an Avast Sandbox flaw that dumps the SAM database for a SYSTEM shell (Gen Digital is developing a patch), and GreenSection, an Nvidia memory corruption bug that crashes systems. CrowdStrike advises customers to disable the Suspicious Macro Removal Windows policy while it investigates.
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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.
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Researcher Releases FalconFlank PoC Showing Privilege Escalation in CrowdStrike Falcon
Researcher Chaotic Eclipse released FalconFlank, a zero-day privilege escalation PoC abusing CrowdStrike Falcon's Office macro remediation; CrowdStrike is investigating and issued a tech alert.
Researcher Chaotic Eclipse published FalconFlank, a proof-of-concept zero-day local privilege escalation in CrowdStrike Falcon Sensor that abuses the Microsoft Office malicious macros remediation feature, tested on fully updated Windows 11 25H2 and Windows Server 2025. CrowdStrike said it is investigating, advised disabling the Microsoft Office File Suspicious Macro Removal policy, and pointed customers to a FalconFlank tech alert, noting cloud anti-malware protection remains active. The article also covers related PoCs from the same researcher: HardBreacher against Kaspersky (fixed via update), ShieldBreak (CVE-2026-69414) against Microsoft Defender, an unpatched patch bypass of CVE-2026-50656, GreenSection against NVIDIA, and PrettyPrague against Avast, which Gen Digital patched in versions 26.7.11086 and 26.8.11125.
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Microsoft Defender's Own Driver Can Be Weaponized to Delete Security Software at Boot
Check Point revealed BTR Reforged, a technique weaponizing Microsoft Defender's built-in BTR.sys driver to delete security software at boot without exploiting any vulnerability.
Check Point Research disclosed BTR Reforged, a technique that abuses BTR.sys, a legitimately signed Windows Defender boot-time remediation driver, to perform arbitrary kernel-level file and registry operations on Windows 7 through Windows 11 25H2 without exploiting a software flaw. The BTR_CLI proof-of-concept tool, presented at Black Hat USA 2026 and DEF CON 34, installs the driver via direct registry writes and executes deletions during the boot-time 'golden window' before Defender's user-mode services start, demonstrated by deleting the full Defender stack on a patched Windows 11 machine. Exploitation requires SeLoadDriverPrivilege; Microsoft confirmed it does not meet criteria for immediate servicing and no patch is planned. No evidence of real-world abuse was found, and related indicators of compromise via Sysmon events were published.
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Risky Bulletin: Expired cards can be used for new transactions
Researchers show expired Visa contactless cards can be revived via NFC man-in-the-middle relay to run fraudulent transactions; roundup also covers major breaches.
University of Massachusetts Amherst researchers built an NFC man-in-the-middle rig that updates a card's expiration date in transit and relays the modified payment to POS terminals, reviving expired contactless cards; Visa terminals and the backends of all five banks studied failed to catch the manipulation. The same roundup reports Iranian hackers shut down a small UK power plant for four days, Lazarus breached South Korea's Presidential Office as part of a campaign exceeding 100 victims, and French telecom SFR suffered a breach affecting over 2.1 million customers.
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Week in review: Records allegedly stolen from Azure tenants, Medusa ransomware hits 500+ orgs
Week in review: Medusa ransomware hit 500+ orgs per CISA, millions of Azure tenant records allegedly stolen, SafePal and French tax authority breaches disclosed.
Help Net Security's weekly roundup covers the FBI, CISA, and HHS joint advisory update reporting Medusa ransomware has breached more than 500 organizations since June 2021, and threat actor TheHatman's claim of millions of employee records stolen from Azure tenants of Fortune 500 firms including McDonald's, Vodafone, Kyndryl, and Tata Consultancy Services, per Hudson Rock. It also covers the SafePal breach affecting 39,798 customers, France's DGFiP breach exposing data on 678,000 individuals, and UT San delaying its fall semester after a cyberattack. Security items include critical unauthenticated GitLab flaw CVE-2026-19478, an actively exploited patched macOS Screen Sharing flaw deploying a cryptominer, US charges against 17 Mabna Institute Iranian hackers over 31TB of stolen academic data, and Google Mandiant's AI agents finding 100+ high-severity vulnerabilities.
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Chaotic Eclipse Released GreenSection, A PoC For NVIDIA Memory Corruption Zero-Day
Researcher Chaotic Eclipse released GreenSection, a PoC exploiting an unpatched out-of-bounds write in NVIDIA Windows user-mode shared memory.
Security researcher Chaotic Eclipse disclosed an out-of-bounds write in NVIDIA's Windows user-mode components, which share a global memory section (\BaseNamedObjects\{52813408-3561-4705-820a-2b3b78be92ba}) with full read/write access to all users. The PoC crashes applications running Vulkan or OpenGL; the researcher says the bug could cross user boundaries or compromise dwm.exe but did not fully assess the impact. No CVE has been assigned and no patch is mentioned. The researcher recently released zero-day PoCs against Kaspersky, Avast, and CrowdStrike Falcon.
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Serial Microsoft 0-day hunter drops yet another Defender exploit
Researcher Nightmare Eclipse released ShieldCrash, a Microsoft Defender zero-day PoC that bypasses September patches and reads files as SYSTEM.
Zero-day researcher Nightmare Eclipse (MSNightmare) published ShieldCrash, their 11th Microsoft zero-day, a proof-of-concept bypass of the ShieldBreak patch (CVE-2026-69414), which itself had bypassed the fix for RoguePlanet (CVE-2026-50656). ShieldCrash works on Windows 10, Windows 11, and Windows Server systems that have applied the September 2026 patches and allows arbitrary file reads as SYSTEM, though not arbitrary writes or a full SYSTEM shell. Microsoft has not said when it plans to patch the issue. The researcher recently also released zero-days affecting CrowdStrike Falcon (FalconFlank), Kaspersky endpoint antivirus (HardBreacher, patched), and Gen Digital's Avast (PrettyPrague).
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