Windows 11 affected by a bug that can cause performance slowdowns and data loss, even on new PCs

Microsoft has already come back with an update-to-update for Windows 11 that fixes the source of the inconvenience, but not the damage caused.

So, if you installed Microsoft’s recently released “June 2022” package of security updates for Windows 11 and Windows Server 2022 platforms, you may find yourself losing important data and encountering other problems with PC operation. The good news is that the problem can be solved by applying the latest updates distributed through the Windows Update channel. The bad news is that any data loss not covered by an automatic backup policy could remain permanent, as the bug involves irreversible data encryption.

Apparently, the problem is related to the implementation of the Vector Advanced Encryption Standard (VAES) instruction set, responsible for speeding up cryptographic operations. Microsoft says that the affected systems use AES-XTS or AES-GCM instructions “on new hardware”. Part of the AVX-512 instruction set , VAES instructions are supported by Intel’s Ice Lake, Tiger Lake, Rocket Lake and Alder Lake architectures – these associated with some 10th generation Core processors for laptops, as well as all 11th and 12th generations. AMD’s upcoming Zen 4 architecture also supports VAES, but it’s unclear if the bug manifests for these as well. Most likely, by the time these chips are released in the fall, patches will already be widely distributed and applied. It remains to be seen, with what performance penalties.

Microsoft says the problem arose from the introduction of “new code” needed to support updated encryption instructions in SymCrypt , Windows’ library of cryptographic functions. These code paths were added in the initial version of Windows 11 and Windows Server 2022, so the issue shouldn’t affect older versions such as Windows 10 or Windows Server 2019.

The initial fix to this failed patch was distributed as early as June, but the issue was not resolved quickly and on time for all affected PCs. The bad news is that the fix involves a permanent performance penalty the fix completely disabling encryption acceleration on these processors. Using Bitlocker or Transport Layer Security (TLS) encrypted disks or accessing encrypted storage on servers will be slower with the first patch installed, although installing the July 2022 security updates (Windows 11 build 22000.795) should restore functionality to the previous level.