CVE-2026-99176
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry Reset the vCPU's MMU pointer back to the root MMU if loading L2 state fails in the "not from VM-Entry" case, i.e. when emulating RSM or handling KVM_SET_NESTED_STATE. Failure to unwind the MMU pointer results in KVM trying to run L1 with a nested MMU, and is especially problematic if the vCPU manages to free its nested state before the VM crashes. Constructing the root for a nested EPT MMU goes through vmcs12, which is dynamically allocated/freed when nVMX is enabled/disabled. And so if the nested state is freed with the MMU still pointing at the nested MMU, KVM will hit a NULL pointer deref when attempting to get L1=>L2 EPTP. BUG: kernel NULL pointer dereference, address: 0000000000000078 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 114a2d067 P4D 111743067 PUD 11141f067 PMD 0 Oops: Oops: 0000 [#1] SMP CPU: 20 UID: 1000 PID: 1272 Comm: nested_tdp_faul Not tainted 7.3.0-rc4-8c89f11d1a99b-sink-vm #1914 PREEMPTLAZY Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel] Call Trace: <TASK> kvm_mmu_load+0xcd/0x870 [kvm] kvm_arch_vcpu_ioctl_run+0x18f5/0x1f80 [kvm] kvm_vcpu_ioctl+0x2c7/0x970 [kvm] __x64_sys_ioctl+0x90/0xd0 do_syscall_64+0x9c/0x4d0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x47491b </TASK> Modules linked in: kvm_intel kvm irqbypass CR2: 0000000000000078 ---[ end trace 0000000000000000 ]--- RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel] [sean: write changelog]
View original CVE JSON
{
"id": "CVE-2026-99176",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-10-28T11:17:38.270",
"lastModified": "2026-10-28T11:17:38.270",
"vulnStatus": "Received",
"cveTags": [],
"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": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"arch/x86/kvm/vmx/nested.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
"lessThan": "d00d5f534a8238674755e59826a6c7d3c8efb870",
"versionType": "git",
"status": "affected"
},
{
"version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
"lessThan": "c9716f956216eb74ab0aad7f633586edd49e0322",
"versionType": "git",
"status": "affected"
},
{
"version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
"lessThan": "c8f4cfe1cf93bce924e27f2abead7a4c4a487505",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"arch/x86/kvm/vmx/nested.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "4.15",
"status": "affected"
},
{
"version": "0",
"lessThan": "4.15",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.59",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.13",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/c8f4cfe1cf93bce924e27f2abead7a4c4a487505",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c9716f956216eb74ab0aad7f633586edd49e0322",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d00d5f534a8238674755e59826a6c7d3c8efb870",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}