Microsoft found a problem in Windows 11 and Windows Server 2022 which opens the door to data corruption when using the encryption instruction introduced in modern processors: Vector Advanced Encryption Standard (VAES). The company hasn’t released an official list of processors that can trigger the bug, but it could be extensive.

The Redmond giant explained that “Windows devices that support the latest Vector Advanced Encryption Standard (AES) (VAES) instruction set may be vulnerable to data corruption“. Affected devices use one of two encryption modes: AES-XTS or AES-GCM.

According to its version, Microsoft has been aware of the problem for a long time, as it released the security patch on May 24, 2022 as early and on June 14, 2022 as stable to avoid data corruption. However, it wasn’t all good news at first, as the update could lead to performance loss after a month of application on Windows 11 and Windows Server 2022. Performance loss or degradation could be felt on BitLocker, TLS (specifically on load balancers) and itself disk performance, especially for business clients.

The data corruption was resolved, but the performance loss remained. The company immediately went to work with the intention of releasing next security patch in preview on June 23, 2022 and as stable on July 12, 2022so if Microsoft followed through on their plan, the issue should be resolved.

Patches that definitively resolve the encryption usage issue have been distributed through the following updates:

• Preliminary version (preview release): KB5014668 on Windows 11 and KB5014665 on Windows Server 2022.
• Security releases: KB5015814 on Windows 11 and KB5015827 on Windows Server 2022.

Going back to VAES, which is ultimately the source of the bug that concerns us in this post, the first generation of Intel processors to introduce support for the instruction was Ice Lake. On AMD’s part, Zen 3-based Ryzen 5000 processors at least have support triggering a bug discovered in the latest generation of Windows operating systems.

And for now, another part of the problems that have already become a habit since the release of Windows 10. Although no operating system is perfect, what is happening with Microsoft’s product has become a habit that some people are beginning to be uncomfortable with.