Microsoft engineers have warned that devices running Windows 11 and Windows Server 2022 with the latest supported processors may be susceptible to some sort of “data corruption”. While the company warns about the risk of data loss, it doesn’t specify exactly what customers can expect if they encounter this issue.
The company said in a statement that the problem applies to Windows devices that support the latest Vector Advanced Encryption Standard (VAES) instruction set. Running on the latest hardware, these devices use AES-XTS or AES-GCM block cipher modes.
Microsoft assures that the issue has already been resolved in the previews and patches released on May 24 and June 14, 2022, and further data corruption will not occur. However, these updates can have a significant performance impact: after installing them, AES-based operations can run up to half as slow on systems running Windows Server 2022 and Windows 11.
Scenarios that are affected by performance degradation may include BitLocker, TLS (in particular load balancers), and disk throughput (especially for enterprise customers).
“We have added new code paths in SymCrypt for the original release of Windows 11 and Windows Server 2022 to take advantage of VAES (Vectorized AES) instructions. SymCrypt is the core Windows cryptographic library. These instructions affect the Advanced Vector Extensions (AVX) registers for hardware with the latest supported processors.
Users experiencing performance issues are advised to install the June 23, 2022 preview updates for Windows 11 and Windows Server 2022 or the July 12, 2022 security updates for Windows 11 and Windows Server 2022. Microsoft says these updates will restore original performance and also help “prevent further damage”.