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

Summary

A security researcher, Chaotic Eclipse, has released a proof-of-concept (PoC) for a new vulnerability in Microsoft Defender, dubbed ShieldCrash. This vulnerability is a bypass for a previously patched issue (CVE-2026-69414, ShieldBreak), allowing for arbitrary file reads as SYSTEM. Despite Microsoft's recent update to the Malware Protection Engine, the researcher claims a specific condition still allows exploitation.

Full text

Researcher Drops New Microsoft Defender PoC Showing ShieldBreak Patch Can Be Bypassed Ravie LakshmananSep 09, 2026Vulnerability / Endpoint Security The security researcher known as Chaotic Eclipse has dropped a proof-of-concept (PoC) for yet another zero-day in Microsoft Defender. The vulnerability, codenamed ShieldCrash, is assessed to be a patch bypass for CVE-2026-69414 (CVSS score: 7.8), also called ShieldBreak, which the researcher reported last month. "Microsoft has failed to properly patch ShieldBreak CVE-2026-69414," Chaotic Eclipse said. "Under specific conditions it is still possible to trigger the exact same problem that was caused by ShieldBreak. While Microsoft fixed several things to prevent re-exploiting the issue, they missed a spot where ShieldBreak can still be exploited." The PoC demonstrates an arbitrary file read as SYSTEM with the latest version of Windows installed. All supported versions of the desktop operating system are said to be impacted. The development comes days after Redmond shipped an update to the Microsoft Malware Protection Engine to plug CVE-2026-69414. The issue has been patched in Malware Protection Engine version 1.1.26080.3. It does not require any customer action and does not affect systems that have disabled Microsoft Defender. "In response to a constantly changing threat landscape, Microsoft frequently updates malware definitions and the Microsoft Malware Protection Engine," the tech giant said. "In order to be effective in helping protect against new and prevalent threats, antimalware software must be kept up to date with these updates in a timely manner." "For enterprise deployments as well as end users, the default configuration in Microsoft antimalware software helps ensure that malware definitions and the Microsoft Malware Protection Engine are kept up to date automatically. Product documentation also recommends that products are configured for automatic updating." In recent weeks, Chaotic Eclipse has also released PoC exploits for four vulnerabilities impacting CrowdStrike Falcon Sensor (FalconFlank), Kaspersky (HardBreacher), Avast Antivirus (PrettyPrague), and NVIDIA (GreenSection). Both HardBreacher and PrettyPrague have since been patched by the respective security vendors, while CrowdStrike told The Hacker News that it's investigating the report. Found this article interesting? Follow us on Google News, Twitter and LinkedIn to read more exclusive content we post. SHARE     Tweet Share Share Share SHARE  endpoint security, Microsoft, Vulnerability, Windows ⚡ Top Stories This Week Attackers Exploit Critical Langflow and Rails Flaws in Credential-Probing and C2 Activity Iranian Hackers Pose as Recruiters to Deliver Cross-Platform RATs Through Coding Tests ⚡ Weekly Recap: Chrome 0-Day, Router Hijacks, Coder Supply Chain Attack and More N-able Issues Fourth N-central Hotfix in Five Weeks for Unauthenticated RCE Flaw Attackers Hijack MikroTik Routers Through Internet-Exposed SSH Without Authentication Unpatched Magento and Adobe Commerce Zero-Day Exploited to Backdoor Online Stores Attackers Breached JetBrains Cadence via Unpatched TeamCity, Extracting AWS Credentials Critical VMware Workstation and Fusion Flaw Lets VM Admins Execute Host Code Thousands of OpenAI Agents Quietly Turned an Abandoned Wiki Into Their Coordination Channel Attackers Exploit PaperCut Flaws to Steal Credentials From Schools and Universities Phishing Campaign Sends Millions of Emails Using Invisible Unicode to Evade Filters PostgreSQL Fixes 12-Year-Old Logical Decoding Flaw Enabling Replication-Role Code Execution New Ted Backdoor Hides Inside Victims' Own HAProxy Builds to Intercept Web Traffic Google Releases Chrome Update to Patch Actively Exploited V8 Zero-Day ThreatsDay: CEO Phishing Kits, 5K Dropbox Account Hacks, OAuth Traps + 17 More Stories Critical Cisco Nexus 9000 Flaw Lets Unauthenticated Remote Attackers Run Code as Root Thomson Reuters Court Software Breach May Have Exposed SSNs and Sealed Data Pegasus Zero-Click Spyware Exploit Infects Serbian Student Movement Member's iPhone Researcher Releases FalconFlank PoC Showing Privilege Escalation in CrowdStrike Falcon Fake Software Installers Disable Windows Update and Weaken Microsoft Defender Malicious .git Configs Can Make Claude, Codex, Cursor, and Other AI Agents Run Attacker Code Meta Ads Push StreamRat Android Trojan That Can Gain Near-Complete Device Control Attackers Exploit Two SonicWall SMA 1000 Zero-Days That May Form an Attack Chain GeoNetwork Fixes Unauthenticated RCE Chain Affecting Government Geoportal Backends Researchers Use Claude to Port Pre-Auth RCE Exploit From One PLC Model to Another ⭐ Featured Resources Get the eBook: Map Enterprise AI Risk Across the Full Lifecycle Give SOC Analysts Visibility Into 90% of Attacks Within 60 Seconds Benchmark Your SOC's AI Adoption With the 2026 Security Operations Report Register for LDR516: Strategic Vulnerability and Threat Management at SANS DC Metro

Indicators of Compromise

• cve — CVE-2026-69414

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