{"id":"CVE-2026-99176","state":"PUBLISHED","title":"KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry\n\nReset the vCPU's MMU pointer back to the root MMU if loading L2 state fails\nin the \"not from VM-Entry\" case, i.e. when emulating RSM or handling\nKVM_SET_NESTED_STATE.  Failure to unwind the MMU pointer results in KVM\ntrying to run L1 with a nested MMU, and is especially problematic if the\nvCPU manages to free its nested state before the VM crashes.  Constructing\nthe root for a nested EPT MMU goes through vmcs12, which is dynamically\nallocated/freed when nVMX is enabled/disabled.  And so if the nested state\nis freed with the MMU still pointing at the nested MMU, KVM will hit a NULL\npointer deref when attempting to get L1=>L2 EPTP.\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000078\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  PGD 114a2d067 P4D 111743067 PUD 11141f067 PMD 0\n  Oops: Oops: 0000 [#1] SMP\n  CPU: 20 UID: 1000 PID: 1272 Comm: nested_tdp_faul Not tainted 7.3.0-rc4-8c89f11d1a99b-sink-vm #1914 PREEMPTLAZY\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n  RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel]\n  Call Trace:\n   <TASK>\n   kvm_mmu_load+0xcd/0x870 [kvm]\n   kvm_arch_vcpu_ioctl_run+0x18f5/0x1f80 [kvm]\n   kvm_vcpu_ioctl+0x2c7/0x970 [kvm]\n   __x64_sys_ioctl+0x90/0xd0\n   do_syscall_64+0x9c/0x4d0\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\n  RIP: 0033:0x47491b\n   </TASK>\n  Modules linked in: kvm_intel kvm irqbypass\n  CR2: 0000000000000078\n  ---[ end trace 0000000000000000 ]---\n  RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel]\n\n[sean: write changelog]","publishedAt":"2026-10-28T10:35:30.615Z","updatedAt":"2026-10-30T12:42:40.156Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"c2586874605ec23b611c57fe71d183d98f168971","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"c611337aee17a0627e365e58e2b6e78803fb3c36","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"df4d01be5b318024bec68654c7af0ebc0e0ed8a1","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"6a36b05fc5b3d660fcc826133dc92e2fc87bd1de","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"f0c077c36fda9d498db39199e3997860e985efc8","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"d00d5f534a8238674755e59826a6c7d3c8efb870","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"c9716f956216eb74ab0aad7f633586edd49e0322","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"c8f4cfe1cf93bce924e27f2abead7a4c4a487505","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/vmx/nested.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.15","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.161","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.115","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.59","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","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/vmx/nested.c"]}],"references":["https://git.kernel.org/stable/c/c2586874605ec23b611c57fe71d183d98f168971","https://git.kernel.org/stable/c/c611337aee17a0627e365e58e2b6e78803fb3c36","https://git.kernel.org/stable/c/df4d01be5b318024bec68654c7af0ebc0e0ed8a1","https://git.kernel.org/stable/c/6a36b05fc5b3d660fcc826133dc92e2fc87bd1de","https://git.kernel.org/stable/c/f0c077c36fda9d498db39199e3997860e985efc8","https://git.kernel.org/stable/c/d00d5f534a8238674755e59826a6c7d3c8efb870","https://git.kernel.org/stable/c/c9716f956216eb74ab0aad7f633586edd49e0322","https://git.kernel.org/stable/c/c8f4cfe1cf93bce924e27f2abead7a4c4a487505"],"weaknesses":[],"ingestedAt":"2026-10-30T13:02:04.640Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99176.json","commit":"cb14bf1b43b0c9f05f7f40eae2246263fd430780","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99176","state":"PUBLISHED","datePublished":"2026-10-28T10:35:30.615Z","dateUpdated":"2026-10-30T12:42:40.156Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.399Z"},"containers":{"cna":{"title":"KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry\n\nReset the vCPU's MMU pointer back to the root MMU if loading L2 state fails\nin the \"not from VM-Entry\" case, i.e. when emulating RSM or handling\nKVM_SET_NESTED_STATE.  Failure to unwind the MMU pointer results in KVM\ntrying to run L1 with a nested MMU, and is especially problematic if the\nvCPU manages to free its nested state before the VM crashes.  Constructing\nthe root for a nested EPT MMU goes through vmcs12, which is dynamically\nallocated/freed when nVMX is enabled/disabled.  And so if the nested state\nis freed with the MMU still pointing at the nested MMU, KVM will hit a NULL\npointer deref when attempting to get L1=>L2 EPTP.\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000078\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  PGD 114a2d067 P4D 111743067 PUD 11141f067 PMD 0\n  Oops: Oops: 0000 [#1] SMP\n  CPU: 20 UID: 1000 PID: 1272 Comm: nested_tdp_faul Not tainted 7.3.0-rc4-8c89f11d1a99b-sink-vm #1914 PREEMPTLAZY\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n  RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel]\n  Call Trace:\n   <TASK>\n   kvm_mmu_load+0xcd/0x870 [kvm]\n   kvm_arch_vcpu_ioctl_run+0x18f5/0x1f80 [kvm]\n   kvm_vcpu_ioctl+0x2c7/0x970 [kvm]\n   __x64_sys_ioctl+0x90/0xd0\n   do_syscall_64+0x9c/0x4d0\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\n  RIP: 0033:0x47491b\n   </TASK>\n  Modules linked in: kvm_intel kvm irqbypass\n  CR2: 0000000000000078\n  ---[ end trace 0000000000000000 ]---\n  RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel]\n\n[sean: write changelog]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"c2586874605ec23b611c57fe71d183d98f168971","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"c611337aee17a0627e365e58e2b6e78803fb3c36","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"df4d01be5b318024bec68654c7af0ebc0e0ed8a1","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"6a36b05fc5b3d660fcc826133dc92e2fc87bd1de","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"f0c077c36fda9d498db39199e3997860e985efc8","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"d00d5f534a8238674755e59826a6c7d3c8efb870","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"c9716f956216eb74ab0aad7f633586edd49e0322","versionType":"git"},{"version":"72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778","status":"affected","lessThan":"c8f4cfe1cf93bce924e27f2abead7a4c4a487505","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/vmx/nested.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.15","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.161","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.115","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.59","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","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/vmx/nested.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c2586874605ec23b611c57fe71d183d98f168971"},{"url":"https://git.kernel.org/stable/c/c611337aee17a0627e365e58e2b6e78803fb3c36"},{"url":"https://git.kernel.org/stable/c/df4d01be5b318024bec68654c7af0ebc0e0ed8a1"},{"url":"https://git.kernel.org/stable/c/6a36b05fc5b3d660fcc826133dc92e2fc87bd1de"},{"url":"https://git.kernel.org/stable/c/f0c077c36fda9d498db39199e3997860e985efc8"},{"url":"https://git.kernel.org/stable/c/d00d5f534a8238674755e59826a6c7d3c8efb870"},{"url":"https://git.kernel.org/stable/c/c9716f956216eb74ab0aad7f633586edd49e0322"},{"url":"https://git.kernel.org/stable/c/c8f4cfe1cf93bce924e27f2abead7a4c4a487505"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:42:40.156Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.6.161"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.18.59"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}