BigDiskBuster Zero-Day PoC Published, Blocks Microsoft Defender Updates
GitHub tool exploits disk space limitation to prevent Defender platform and signature updates; no patch or CVE available

Key Takeaways
- A zero-day PoC tool named BigDiskBuster was published on GitHub on September 19, 2026.
- The tool exploits a design limitation in Microsoft Defender by filling all available disk space.
- This blocks the installation of critical platform and signature updates for Microsoft Defender.
- No CVE, patch, or Microsoft advisory has been issued at the time of disclosure.
Related Security News

Star Blizzard Campaign Targets 100+ Organizations with Fake Event Invitations
Microsoft reports that the Russian state-sponsored threat actor Star Blizzard has been conducting a sustained campaign since January 2026, using fake event invitations to trick targets into installing a backdoor on Windows computers. The operation has affected more than 100 organizations, primarily in the U.S. and U.K., with victims tied to Ukraine. At least one infection has been confirmed, though the full extent of breaches and data exfiltration remains unverified.




