CVE-2026-64284

Summary

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits

Move the handling of fastpath userspace exits into vendor code to ensure KVM runs vendor specific operations that need to run before userspace gains control of the vCPU. E.g. for VMX (and soon to be for SVM as well), KVM needs to flush the PML buffer prior to exiting to userspace, otherwise any memory written by the final KVM_RUN might never be flagged as dirty.

Note, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in general, as that risks consuming stale state in a fastpath handler. That will be addressed in a future change.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxf7f39c50edb9d336274371953275e0d3503b9b75 < b3436d9b9b1affe1c3191ac9831308923f5f03c3affected
LinuxLinuxf7f39c50edb9d336274371953275e0d3503b9b75 < 4ad73ef0e7966ecfe67de0060537b4cb14d9acd4affected
LinuxLinuxf7f39c50edb9d336274371953275e0d3503b9b75 < f2ca2b5326211bd38490f0497eb583721ce0bbc0affected
LinuxLinuxf7f39c50edb9d336274371953275e0d3503b9b75 < 0ffedf43910e44b76c2c1db4e9fbf12b268190c1affected
LinuxLinux6.12affected
LinuxLinux0 < 6.12unaffected
LinuxLinux6.12.96 <= 6.12.*unaffected
LinuxLinux6.18.39 <= 6.18.*unaffected
LinuxLinux7.1.4 <= 7.1.*unaffected
LinuxLinux7.2-rc1 <= *unaffected

Weaknesses

References