Three Microsoft Secure Boot Certificates Expire June 24. Windows and Linux Users Need to Act.
On June 24, 2026, three Microsoft-signed certificates that underpin Secure Boot will expire, leaving unpatched Windows and Linux systems exposed to firmware-level malware that loads before any antivirus software can run. This is a concrete, dated deadline. Users and IT administrators who have not applied relevant firmware and OS updates need to do so before Tuesday.