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New ‘ShieldCrash’ Zero-Day Exploit Targets Microsoft Defender

Researcher Nightmare Eclipse released ShieldCrash, a Microsoft Defender zero-day PoC bypassing ShieldBreak patches to gain System privileges on Windows.

The researcher known as Nightmare Eclipse released a PoC zero-day exploit dubbed ShieldCrash against Microsoft Defender on fully patched Windows systems. The exploit grants arbitrary file read with System privileges and can be used to drop the SAM database. It bypasses Microsoft's September 3 fixes for ShieldBreak (CVE-2026-69414), which itself bypassed patches for the RoguePlanet race condition (CVE-2026-50656). Microsoft has been contacted for comment and has not yet responded.

SecurityWeekupdated · 6d agofirst · 6d agoExploit / PoC 2 sourcesCVE-2026-50656CVE-2026-694141

Windows Defender ShieldCrash 0-Day Lets Attackers Read Arbitrary Files as SYSTEM

Unpatched Windows Defender zero-day 'ShieldCrash' PoC lets local attackers read arbitrary files as SYSTEM, apparently bypassing the CVE-2026-69414 patch.

Researcher MSNightmare published a skeleton proof-of-concept for 'ShieldCrash', an unpatched Microsoft Defender flaw enabling arbitrary file reads with SYSTEM privileges that reportedly persists on supported Windows versions after September 2026 updates. It appears to bypass the recent fix for the Malware Protection Engine elevation-of-privilege flaw CVE-2026-69414 (ShieldBreak), patched in engine version 1.1.26080.3. SYSTEM-level file disclosure could expose credentials, application secrets and registry hives and support post-compromise reconnaissance. No active exploitation is confirmed and Microsoft had issued no specific patch or mitigation at disclosure time.

GBHackers · 7d agoExploit / PoCCVE-2026-69414

Chaotic Eclipse Released ShieldCrash, A PoC For Microsoft Defender Zero-Day

Researcher Chaotic Eclipse released ShieldCrash, a PoC showing Microsoft Defender's CVE-2026-69414 patch is incomplete, enabling arbitrary file reads as SYSTEM.

Security researcher Chaotic Eclipse published ShieldCrash, a proof-of-concept exploit for the Microsoft Malware Protection Engine privilege escalation vulnerability CVE-2026-69414 (ShieldBreak). The PoC performs arbitrary file reads with SYSTEM privileges on all supported Windows versions, including systems running the September 2026 security updates and Malware Protection Engine version 1.1.26080.3. The researcher claims Microsoft's patch fixed several exploit paths but missed a specific condition that still enables the attack. His recent releases also include zero-day PoCs targeting Nvidia, Kaspersky, Avast, and CrowdStrike Falcon.

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).

New Microsoft Defender 'ShieldCrash' zero-day grants SYSTEM access

Researcher Nightmare Eclipse released 'ShieldCrash', a zero-day exploit for Microsoft Defender that grants attackers SYSTEM-level access.

An anonymous researcher known as Nightmare Eclipse published a zero-day exploit for Microsoft Defender, dubbed 'ShieldCrash', that yields SYSTEM-level access. The release came immediately after Microsoft rolled out its September 2026 Patch Tuesday security updates. No CVE identifier has been assigned publicly and no in-the-wild exploitation has been reported yet. Microsoft Defender ships by default on Windows, so potential exposure is broad until Microsoft patches the flaw.

BleepingComputer · 7d agoExploit / PoC

Nightmare-Eclipse Strikes Again with 'ShieldCrash' Windows Exploit

A researcher known as Nightmare-Eclipse published another zero-day exploit, dubbed ShieldCrash, targeting Windows Defender.

Dark Reading reports that the disgruntled researcher tracked as Nightmare-Eclipse continued a vendetta against Microsoft by publishing a new zero-day exploit named ShieldCrash for Windows Defender. The brief report does not detail affected versions, exploitation prerequisites, or whether exploitation has been observed.

Dark Reading · 6d agoExploit / PoC1

Weekly Cybersecurity Newsletter Bulletin – Microsoft 0-day, FortiOS, PAN-OS Flaw, Revolut Data Breach, and 20+ Stories

Weekly roundup: Microsoft patches 973 flaws including two actively exploited zero-days; FortiOS CAPWAP flaw deploys PivotC2 RAT; PAN-OS root RCE disclosed.

Microsoft's September 2026 Patch Tuesday fixed 973 vulnerabilities, including two zero-days under active exploitation: CVE-2026-85880 (Windows ALPC) and CVE-2026-81963 (Windows Update Stack), both elevation-of-privilege bugs. SOCRadar reported active exploitation of CVE-2025-25249 (CVSS 9.8) in FortiOS CAPWAP, deploying a Node.js RAT called PivotC2 that exfiltrates Exchange mailboxes to Wasabi cloud storage; 178 devices were compromised out of 30,000 scanned IPs, attributed to a Russian-speaking financially motivated group. Palo Alto disclosed CVE-2026-0310, a 9.2-rated buffer overflow enabling root code execution on PA-Series firewalls, and Fortinet disclosed CVE-2026-84393, a ZTNA certificate validation MITM flaw. Cyera also revealed CVE-2026-6471 ('PostGREShell'), a 12-year-old PostgreSQL logical-decoding flaw allowing code execution via REPLICATION-privileged accounts.

PaperCut Flaws Exploited in AI-Powered Attacks

GreyNoise says a Russian-speaking actor used AI to build and deploy exploits hitting 440 PaperCut NG/MF deployments across 395 organizations in 48 countries.

Two PaperCut NG/MF zero-days, CVE-2026-82078 and CVE-2026-81578, disclosed August 27 and patched August 28, enable unauthenticated authentication bypass and remote code execution. GreyNoise observed a Russian-speaking threat actor using AI to orchestrate attacks against 440 deployments in 48 countries, including 204 education-sector organizations, achieving domain admin at 12 victims. Attack paths included harvesting LSASS memory and registry secrets, mounted NoPac attacks, and adding accounts to Domain Admins, with AI automation shortening compromises to minutes or seconds.

SecurityWeekupdated · 5d agofirst · 5d agoExploit / PoC in the wild 7 sourcesCVE-2026-82078CVE-2026-81578

Critical NetScaler Vulnerability Exploited in Attacks

CISA added critical Citrix NetScaler flaw CVE-2026-19490 (CVSS 9.3) to its KEV catalog after confirming exploitation of gateway and AAA virtual servers in the wild.

CISA warned that threat actors are exploiting CVE-2026-19490, a critical-severity flaw (CVSS 9.3) affecting NetScaler ADC and NetScaler Gateway appliances configured as a gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server. Citrix patched the bug on August 19, and Rapid7 warned it is remotely exploitable without authentication. Sensor data from Previdian shows exploitation ongoing since at least September 3, one day after a public exploit appeared on GitHub, with matching requests observed from three IPs across three countries. CISA added the flaw to its Known Exploited Vulnerabilities catalog, giving federal agencies three days to patch under BOD 26-04.

SecurityWeekupdated · 6d agofirst · 6d agoExploit / PoC in the wild 6 sourcesCVE-2026-194902· 2 reads

Researcher Drops New Microsoft Defender PoC Showing ShieldBreak Patch Can Be Bypassed

Researcher Chaotic Eclipse released a PoC showing CVE-2026-69414's patch is bypassable, allowing arbitrary file reads as SYSTEM on current Windows.

The researcher known as Chaotic Eclipse published a proof-of-concept for a zero-day in Microsoft Defender, dubbed ShieldCrash, assessed as a patch bypass for ShieldBreak (CVE-2026-69414, CVSS 7.8). The PoC demonstrates an arbitrary file read as SYSTEM with the latest Windows installed, and all supported desktop versions are said to be impacted. Microsoft patched the original issue in Microsoft Malware Protection Engine 1.1.26080.3, which updates automatically. The same researcher recently released PoCs for flaws in CrowdStrike Falcon Sensor, Kaspersky, Avast Antivirus and NVIDIA.

The Hacker News · 7d agoExploit / PoCCVE-2026-694141