{"id":"CVE-2026-46014","state":"PUBLISHED","title":"KVM: SVM: Add missing save/restore handling of LBR MSRs","description":"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 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]","publishedAt":"2026-05-27T12:56:16.052Z","updatedAt":"2026-10-21T12:41:11.773Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"bca0597272f9712b1f8ebd38b184db1dc2902ff7","versionType":"git"},{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"4428a0a8643b0acf4ed7b8ea3e5975023bf4aafb","versionType":"git"},{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"2b922a42b531a82d7881add14a7698dcdc5e1f0a","versionType":"git"},{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"13a89ada5dcfc2539514c83ba5a2c61157f1ec6c","versionType":"git"},{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"3700f0788da6acf73b2df56690f4b201aa4aefd2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/nested.c","arch/x86/kvm/svm/svm.c","arch/x86/kvm/x86.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.26","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.26","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.27","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.4","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/nested.c","arch/x86/kvm/svm/svm.c","arch/x86/kvm/x86.c"]}],"references":["https://git.kernel.org/stable/c/bca0597272f9712b1f8ebd38b184db1dc2902ff7","https://git.kernel.org/stable/c/4428a0a8643b0acf4ed7b8ea3e5975023bf4aafb","https://git.kernel.org/stable/c/2b922a42b531a82d7881add14a7698dcdc5e1f0a","https://git.kernel.org/stable/c/13a89ada5dcfc2539514c83ba5a2c61157f1ec6c","https://git.kernel.org/stable/c/3700f0788da6acf73b2df56690f4b201aa4aefd2"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/46xxx/CVE-2026-46014.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-46014","state":"PUBLISHED","datePublished":"2026-05-27T12:56:16.052Z","dateUpdated":"2026-10-21T12:41:11.773Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-13T15:03:33.092Z"},"containers":{"cna":{"title":"KVM: SVM: Add missing save/restore handling of LBR MSRs","descriptions":[{"lang":"en","value":"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 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]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"bca0597272f9712b1f8ebd38b184db1dc2902ff7","versionType":"git"},{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"4428a0a8643b0acf4ed7b8ea3e5975023bf4aafb","versionType":"git"},{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"2b922a42b531a82d7881add14a7698dcdc5e1f0a","versionType":"git"},{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"13a89ada5dcfc2539514c83ba5a2c61157f1ec6c","versionType":"git"},{"version":"24e09cbf480a72f9c952af4ca77b159503dca44b","status":"affected","lessThan":"3700f0788da6acf73b2df56690f4b201aa4aefd2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/nested.c","arch/x86/kvm/svm/svm.c","arch/x86/kvm/x86.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.26","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.26","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.27","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.4","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/nested.c","arch/x86/kvm/svm/svm.c","arch/x86/kvm/x86.c"]}],"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"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-21T12:41:11.773Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"6.18.27"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"7.0.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}