BlueHammer

A race condition vulnerability in Windows Defender, known as BlueHammer, has been exploited by the hacker Nightmare Eclipse, allowing attackers to gain SYSTEM user access. Microsoft released a patch for this vulnerability on April 14, but the Cybersecurity and Infrastructure Security Agency (CISA) has flagged it as actively exploited in ransomware campaigns. The average time to apply critical OS patches across Windows 10 and 11 is now 127 days, with enterprise environments averaging 76 days. Estimates suggest that 15% to 26% of Windows 10 machines remain unpatched, with a conservative estimate of 20% translating to one in five machines being vulnerable. Microsoft has extended security updates for Windows 10 until October 14, 2027, but public awareness of the updates remains low.