A security certificate built into every Windows PC and server since 2011 expires on 24 June 2026. Microsoft has been rolling out a replacement automatically, but businesses should confirm their devices are up to date before the deadline.

• What it is: Secure Boot is a feature that checks your computer hasn't been tampered with before Windows loads. The certificate that makes this work expires on 24 June 2026.
• Who is affected: All businesses running Windows PCs and servers. Devices manufactured since 2024 and kept up to date are likely already fine. Older devices or those with deferred updates are most at risk.
• What the risk is: Your computers will still start and work normally after 24 June. However, they will stop receiving future early-boot security protections — including updates that block known malicious bootloaders. Over time this increases vulnerability to a class of attack called bootkits.
• What to do:
  • Ensure Windows Update is running and current on all devices
  • Confirm Secure Boot is enabled in your PC/server firmware settings
  • If your business defers Windows updates centrally, verify the certificate update has not been blocked

If you are unsure whether your devices have received the update, contact your IT provider before 24 June. Sources: Microsoft IT Pro Blog, Malwarebytes