FKIE_CVE-2026-99176

Vulnerability from fkie_nvd - Published: 2026-10-28 11:17 - Updated: 2026-10-30 13:21
Severity
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
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6a36b05fc5b3d660fcc826133dc92e2fc87bd1de
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c2586874605ec23b611c57fe71d183d98f168971
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c611337aee17a0627e365e58e2b6e78803fb3c36
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c8f4cfe1cf93bce924e27f2abead7a4c4a487505
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c9716f956216eb74ab0aad7f633586edd49e0322
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d00d5f534a8238674755e59826a6c7d3c8efb870
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/df4d01be5b318024bec68654c7af0ebc0e0ed8a1
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f0c077c36fda9d498db39199e3997860e985efc8
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "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": "c2586874605ec23b611c57fe71d183d98f168971",
              "status": "affected",
              "version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
              "versionType": "git"
            },
            {
              "lessThan": "c611337aee17a0627e365e58e2b6e78803fb3c36",
              "status": "affected",
              "version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
              "versionType": "git"
            },
            {
              "lessThan": "df4d01be5b318024bec68654c7af0ebc0e0ed8a1",
              "status": "affected",
              "version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
              "versionType": "git"
            },
            {
              "lessThan": "6a36b05fc5b3d660fcc826133dc92e2fc87bd1de",
              "status": "affected",
              "version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
              "versionType": "git"
            },
            {
              "lessThan": "f0c077c36fda9d498db39199e3997860e985efc8",
              "status": "affected",
              "version": "72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778",
              "versionType": "git"
            },
            {
              "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": "5.10.*",
              "status": "unaffected",
              "version": "5.10.273",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.224",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.161",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.115",
              "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"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "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\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]"
    }
  ],
  "id": "CVE-2026-99176",
  "lastModified": "2026-10-30T13:21:51.250",
  "metrics": {},
  "published": "2026-10-28T11:17:38.270",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6a36b05fc5b3d660fcc826133dc92e2fc87bd1de"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c2586874605ec23b611c57fe71d183d98f168971"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c611337aee17a0627e365e58e2b6e78803fb3c36"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "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",
      "url": "https://git.kernel.org/stable/c/df4d01be5b318024bec68654c7af0ebc0e0ed8a1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f0c077c36fda9d498db39199e3997860e985efc8"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.