Microsoft says it's investigating issues with a patch intended to plug a two-year-old flaw in the GRUB open source boot loader that is crashing some dual-boot computers running both Windows and Linux. In that crash users are aptly told: "Something went seriously wrong."

The problems began last week after Microsoft released a security update for CVE-2022-2601, a buffer overflow vulnerability in GRUB 2, a bootloader used by a lot of Linux distributions as well as a number of Windows machines. The flaw could allow rogue users or malware on a system to bypass the Secure Boot feature and load malicious code onto a computer during the startup process.

"The latest builds of Windows are no longer vulnerable to this security feature bypass using the Linux GRUB2 boot loader," the August 13 security advisory from Microsoft noted, adding the update would apply to "dual-boot systems that boot both Windows and Linux and should not affect these systems."

According to numerous forums, however, the patch did apply to these dual-boot systems and then didn't allow Linux distros to boot. As one person posted the day after the update:

In response to The Register's questions, Redmond told us that it is working with its Linux partners to fix the issue.

"This update is not applied when a Linux boot option is detected," a Microsoft spokesperson said. "We are aware that some secondary boot scenarios are causing issues for some customers, including when using outdated Linux loaders with vulnerable code. We are working with our Linux partners to investigate and address."

Following the Patch Tuesday push, complaints from Linux users echoed across Reddit and other websites, with one Linux Mint forum netizen suggesting this Ubuntu workaround:

So until Redmond and friends issue a formal fix, this seems to be the best course of action. ®

https://www.theregister.com//2024/08/21/microsoft_patch_dual_boot/