{"id":"CVE-2026-46014","title":"KVM: SVM: Add missing save/restore handling of LBR MSRs","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Add missing save/restore handling of LBR MSRs\n\nMSR_IA32_DEBUGCTLMSR and LBR MSRs are currently not enumerated by\nKVM_GET_MSR_INDEX_LIST, and LBR MSRs cannot b…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < bca0597272f9712b1f8ebd38b184db1dc2902ff7","Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < 4428a0a8643b0acf4ed7b8ea3e5975023bf4aafb","Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < 2b922a42b531a82d7881add14a7698dcdc5e1f0a","Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < 13a89ada5dcfc2539514c83ba5a2c61157f1ec6c","Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < 3700f0788da6acf73b2df56690f4b201aa4aefd2","Linux 2.6.26"],"published":"2026-05-27","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:41:11.773Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-46014","references":[{"url":"https://git.kernel.org/stable/c/bca0597272f9712b1f8ebd38b184db1dc2902ff7"},{"url":"https://git.kernel.org/stable/c/4428a0a8643b0acf4ed7b8ea3e5975023bf4aafb"},{"url":"https://git.kernel.org/stable/c/2b922a42b531a82d7881add14a7698dcdc5e1f0a"},{"url":"https://git.kernel.org/stable/c/13a89ada5dcfc2539514c83ba5a2c61157f1ec6c"},{"url":"https://git.kernel.org/stable/c/3700f0788da6acf73b2df56690f4b201aa4aefd2"}],"tags":["cve.org"],"epss":0.00124,"epssPercentile":0.01909,"ingestedAt":"2026-10-21T12:48:53.632Z","slug":"CVE-2026-46014","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Add missing save/restore handling of LBR MSRs\n\nMSR_IA32_DEBUGCTLMSR and LBR MSRs are currently not enumerated by\nKVM_GET_MSR_INDEX_LIST, and LBR MSRs cannot be set with KVM_SET_MSRS. So\nsave/restore is completely broken.\n\nFix it by adding the MSRs to msrs_to_save_base, and allowing writes to\nLBR MSRs from userspace only (as they are read-only MSRs) if LBR\nvirtualization is enabled.  Additionally, to correctly restore L1's LBRs\nwhile L2 is running, make sure the LBRs are copied from the captured\nVMCB01 save area in svm_copy_vmrun_state().\n\nNote, for VMX, this also fixes a flaw where MSR_IA32_DEBUGCTLMSR isn't\nreported as an MSR to save/restore.\n\nNote #2, over-reporting MSR_IA32_LASTxxx on Intel is ok, as KVM already\nhandles unsupported reads and writes thanks to commit b5e2fec0ebc3 (\"KVM:\nIgnore DEBUGCTL MSRs with no effect\") (kvm_do_msr_access() will morph the\nunsupported userspace write into a nop).\n\n[sean: guard with lbrv checks, massage changelog]\n\n## Affected\n\n- `Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < bca0597272f9712b1f8ebd38b184db1dc2902ff7`\n- `Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < 4428a0a8643b0acf4ed7b8ea3e5975023bf4aafb`\n- `Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < 2b922a42b531a82d7881add14a7698dcdc5e1f0a`\n- `Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < 13a89ada5dcfc2539514c83ba5a2c61157f1ec6c`\n- `Linux >= 24e09cbf480a72f9c952af4ca77b159503dca44b < 3700f0788da6acf73b2df56690f4b201aa4aefd2`\n- `Linux 2.6.26`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}