CVE-2026-46014KVM: SVM: Add missing save/restore handling of LBR MSRs
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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]
- CVSS
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 21, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 24e09cbf480a72f9c952af4ca77b159503dca44b before bca0597272f9712b1f8ebd38b184db1dc2902ff7; from 24e09cbf480a72f9c952af4ca77b159503dca44b before 4428a0a8643b0acf4ed7b8ea3e5975023bf4aafb; 24e09cbf480a72f9c952af4ca77b159503dca44b builds before 2b922a42b531a82d7881add14a7698dcdc5e1f0a; 24e09cbf480a72f9c952af4ca77b159503dca44b builds before 13a89ada5dcfc2539514c83ba5a2c61157f1ec6c; from 24e09cbf480a72f9c952af4ca77b159503dca44b before 3700f0788da6acf73b2df56690f4b201aa4aefd2 | CNA record |
linux linux_kernel linux:linux_kernel | from 2.6.26 before 6.18.27; from 6.19 before 7.0.4 | NVD |
References
- https://git.kernel.org/stable/c/bca0597272f9712b1f8ebd38b184db1dc2902ff7
- https://git.kernel.org/stable/c/4428a0a8643b0acf4ed7b8ea3e5975023bf4aafb
- https://git.kernel.org/stable/c/2b922a42b531a82d7881add14a7698dcdc5e1f0apatch
- https://git.kernel.org/stable/c/13a89ada5dcfc2539514c83ba5a2c61157f1ec6cpatch
- https://git.kernel.org/stable/c/3700f0788da6acf73b2df56690f4b201aa4aefd2patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.