New Windows Defender ShieldCrash 0-Day Bypasses Microsoft Patch to Read Files as SYSTEM
Researcher's ShieldCrash PoC claims Microsoft Defender still allows arbitrary file reads as SYSTEM on patched Windows, bypassing the CVE-2026-69414 fix.
Researcher MSNightmare released the ShieldCrash proof of concept showing Microsoft Defender can allegedly be made to read arbitrary files with SYSTEM privileges on fully patched Windows systems, bypassing the September 2026 fix for ShieldBreak (CVE-2026-69414). Microsoft has not confirmed the bypass, and the new flaw has no CVE assignment yet. The PoC repository contains C++ project files, a Warden.dll library, and an EICAR test archive, suggesting interaction with Defender's malware-detection and file-handling workflow. Reading files as SYSTEM could expose configuration files, credentials, private keys, and other users' data, though it does not enable code execution.
- PoC claims arbitrary file read as SYSTEM after September 2026 updates
- Bypass of ShieldBreak fix CVE-2026-69414; no new CVE assigned
- Microsoft has not confirmed; claim awaits independent reproduction
- Defenders should watch for unsigned DLLs touching Defender paths
- CVEs
- CVE-2026-69414
- Tags
- arbitrary-file-readmicrosoft-defendermsnightmarepocprivilege-escalationshieldbreakshieldcrashwindows
- Vendors
- Microsoft
- Products
- Microsoft DefenderWindows
- Organizations
- MSNightmare
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-69414 | Local Elevation of Privilege in Microsoft Defender Malware Protection Engine | 7.8 | 1% | PoC |
From the original article
2 min read at cybersecuritynews.com
A newly published ShieldCrash proof of concept from researcher MSNightmare claims that Microsoft Defender remains vulnerable to an arbitrary file-read flaw, despite Microsoft’s earlier fix for ShieldBreak, tracked as CVE-2026-69414. The researcher says the issue could let a local attacker make Defender read files with SYSTEM-level privileges on fully updated, supported Windows systems. According to […]
By Abinaya · cybersecuritynews.com
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