CVE-2026-46014 KVM: SVM: Add missing save/restore handling of LBR MSRs
Missing save/restore handling of LBR MSRs in KVM SVM breaks virtualization state integrity, potentially allowing data corruption or leakage.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-46014?
CVE-2026-46014 is a medium-severity vulnerability in Linux kernel, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Add missing save/restore handling of LBR MSRs
MSR_IA32_DEBUGCTLMSR and LBR MSRs are currently not enumerated by KVM_GET_MSR_INDEX_LIST, and LBR MSRs cannot be set with KVM_SET_MSRS. So save/restore is completely broken.
Fix it by adding the MSRs to msrs_to_save_base, and allowing writes to LBR MSRs from userspace only (as they are read-only MSRs) if LBR virtualization is enabled. Additionally, to correctly restore L1's LBRs while L2 is running, make sure the LBRs are copied from the captured VMCB01 save area in svm_copy_vmrun_state().
Note, for VMX, this also fixes a flaw where MSR_IA32_DEBUGCTLMSR isn't reported as an MSR to save/restore.
Note #2, over-reporting MSR_IA32_LASTxxx on Intel is ok, as KVM already handles unsupported reads and writes thanks to commit b5e2fec0ebc3 ("KVM: Ignore DEBUGCTL MSRs with no effect") (kvm_do_msr_access() will morph the unsupported userspace write into a nop).
[sean: guard with lbrv checks, massage changelog]
Weakness: CWE-667
Which versions are affected by CVE-2026-46014?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46014?
Apply the vendor's patch.
Is CVE-2026-46014 being exploited?
There is no known exploitation of CVE-2026-46014 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-88509, BELL-CVE-2026-46014, DEBIAN-CVE-2026-46014, GHSA-866w-999j-pr8g, ROOT-OS-DEBIAN-11-CVE-2026-46014, ROOT-OS-DEBIAN-12-CVE-2026-46014 and 4 more.