Microsoft's July Patch Tuesday security update rolls out tomorrow, 14 July, with a large batch of fixes and a change that could affect older systems still using legacy authentication.

• What it is: The July 2026 Patch Tuesday release, expected to include somewhere between 100 and 140 vulnerability fixes across Windows and related Microsoft products.
• Who is affected: All Windows business users, and particularly organisations still relying on older Kerberos RC4 encryption, as this release completes Microsoft's final phase of RC4 hardening.
• What's the risk: Systems or applications that still depend on RC4 encryption for authentication may stop working correctly once this update is applied, unless they have already been moved to modern encryption standards.
• What to do: Apply the update through your normal patch management process, but test authentication-dependent systems first if you have older infrastructure still using legacy encryption.

We recommend reviewing your patch management schedule this week to make sure this update is tested and deployed promptly.