CVE-2025-21839

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description A bug in the Linux kernel's KVM (Kernel-based Virtual Machine) implementation allows the guest's DR6 value to be clobbered when the guest modifies DR6 and then a fastpath VM-Exit occurs. This issue primarily affects nested VMX setups, where the window between hardware DR6 being modified and DR6 being read by guest software is larger. The bug can cause the guest's actual DR6 value to be lost.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.