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Fencer Vulns
no cvss —

CVE-2026-99176 json

KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry

published 2026-10-28 11 d ago modified 2026-10-30 9 d ago also EUVD-2026-111928

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

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]

Patch / fix

  • Linux Linux 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3
  • linux Debian 13 6.12.115-2
  • linux Debian 14 7.2.13-1

debian advisories DEBIAN-CVE-2026-99176

  • linux Ubuntu 26.10 7.3.0-10.10
  • linux-aws Ubuntu 26.10 7.3.0-1004.4
  • linux-gcp Ubuntu 26.10 7.3.0-1004.4
  • linux-raspi Ubuntu 26.10 7.3.0-1004.4
  • linux-riscv Ubuntu 26.10 7.3.0-10.10.1
  • linux-oracle Ubuntu 26.10 7.3.0-1004.4
  • linux-realtime Ubuntu 26.10 7.3.0-10.10.1

ubuntu advisories UBUNTU-CVE-2026-99176

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel Azure Linux 3.0 6.6.161.1-1

azure linux advisories AZL-111332

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-99176 updated cvss 6.5

kernel: kernel: Denial of Service via improper MMU reset in KVM nested virtualization

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    +1 more products
    Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.