# CVE-2026-99176: KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** AZL-111332, BELL-CVE-2026-99176, DEBIAN-CVE-2026-99176, GHSA-hq6m-jx84-xxfw, UBUNTU-CVE-2026-99176

## What is CVE-2026-99176?

CVE-2026-99176 is a vulnerability in Linux, published on 28 Oct 2026. 

### Official 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]

## Which versions are affected by CVE-2026-99176?


## How do I fix CVE-2026-99176?

Upgrade to a fixed version.

## Is CVE-2026-99176 being exploited?

There is no known exploitation of CVE-2026-99176 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99176 and fix it if it is affected.

What it is: CVE-2026-99176 is a vulnerability in Linux, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99176 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-99176/ (Markdown: https://insights.sbomify.com/CVE-2026-99176/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99176
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99176
- OSV: https://osv.dev/vulnerability/CVE-2026-99176

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99176/
Summaries are generated and may contain mistakes; the official description above is the record.