CVE-2026-99176 (GCVE-0-2026-99176)
Vulnerability from cvelistv5
Published
2026-10-28 10:35
Modified
2026-10-28 10:35
Severity ?
VLAI Severity ?
EPSS score ?
Summary
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]
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"arch/x86/kvm/vmx/nested.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "d00d5f534a8238674755e59826a6c7d3c8efb870",
"status": "affected",
"version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
"versionType": "git"
},
{
"lessThan": "c9716f956216eb74ab0aad7f633586edd49e0322",
"status": "affected",
"version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
"versionType": "git"
},
{
"lessThan": "c8f4cfe1cf93bce924e27f2abead7a4c4a487505",
"status": "affected",
"version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"arch/x86/kvm/vmx/nested.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.15"
},
{
"lessThan": "4.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.59",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.13",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.59",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.13",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "4.15",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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\u0027s 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=\u003eL2 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 \u003cTASK\u003e\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 \u003c/TASK\u003e\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]"
}
],
"providerMetadata": {
"dateUpdated": "2026-10-28T10:35:30.615Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/d00d5f534a8238674755e59826a6c7d3c8efb870"
},
{
"url": "https://git.kernel.org/stable/c/c9716f956216eb74ab0aad7f633586edd49e0322"
},
{
"url": "https://git.kernel.org/stable/c/c8f4cfe1cf93bce924e27f2abead7a4c4a487505"
}
],
"title": "KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-99176",
"datePublished": "2026-10-28T10:35:30.615Z",
"dateReserved": "2026-09-25T10:25:14.399Z",
"dateUpdated": "2026-10-28T10:35:30.615Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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