Microsoft Update May Fill Windows Hard Drives
A patch released by Microsoft to fix a zero-day vulnerability in Windows Defender may cause Windows machines to write files that consume all available disk space.
Microsoft released a patch on Wednesday to address a zero-day vulnerability in its Defender security engine. However, according to the researcher who discovered the flaw, the fix may result in Windows machines writing files large enough to fill all available disk space.
The vulnerability, tracked as RoguePlanet (CVE-2026-50656), became public in June when a researcher using the pseudonym NightmareEclipse disclosed it along with exploit code. The flaw allows remote attackers to gain administrative control over Windows 10 and Windows 11 machines, even if real-time protection was disabled.
Microsoft stated on Wednesday that the RoguePlanet vulnerability has been fixed with an update to the Microsoft Malware Protection Engine, utilized by the Defender antivirus application. The patch will download and install automatically. Wednesday's update also includes "defense-in-depth updates to help improve security-related features."
This new issue highlights the risks associated with patching vulnerabilities and the need for thorough testing before widespread deployment.