# CVE-2026-46113: KVM: x86: Fix shadow paging use-after-free due to unexpected GFN

> A use-after-free in KVM shadow paging allows local attackers to execute arbitrary code or escalate privileges via crafted guest page table modifications.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-88917, BELL-CVE-2026-46113, DEBIAN-CVE-2026-46113, GHSA-gcf3-9g28-gv44, ROOT-OS-DEBIAN-11-CVE-2026-46113, ROOT-OS-DEBIAN-12-CVE-2026-46113, ROOT-OS-UBUNTU-2204-CVE-2026-46113, ROOT-OS-UBUNTU-2404-CVE-2026-46113, UBUNTU-CVE-2026-46113

## What is CVE-2026-46113?

CVE-2026-46113 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: Fix shadow paging use-after-free due to unexpected GFN

The shadow MMU computes GFNs for direct shadow pages using sp->gfn plus
the SPTE index. This assumption breaks for shadow paging if the guest
page tables are modified between VM entries (similar to commit
aad885e77496, "KVM: x86/mmu: Drop/zap existing present SPTE even
when creating an MMIO SPTE", 2026-03-27).  The flow is as follows:

- a PDE is installed for a 2MB mapping, and a page in that area is
  accessed.  KVM creates a kvm_mmu_page consisting of 512 4KB pages;
  the kvm_mmu_page is marked by FNAME(fetch) as direct-mapped because
  the guest's mapping is a huge page (and thus contiguous).

- the PDE mapping is changed from outside the guest.

- the guest accesses another page in the same 2MB area.  KVM installs
  a new leaf SPTE and rmap entry; the SPTE uses the "correct" GFN
  (i.e. based on the new mapping, as changed in the previous step) but
  that GFN is outside of the [sp->gfn, sp->gfn + 511] range; therefore
  the rmap entry cannot be found and removed when the kvm_mmu_page
  is zapped.

- the memslot that covers the first 2MB mapping is deleted, and the
  kvm_mmu_page for the now-invalid GPA is zapped.  However, rmap_remove()
  only looks at the [sp->gfn, sp->gfn + 511] range established in step 1,
  and fails to find the rmap entry that was recorded by step 3.

- any operation that causes an rmap walk for the same page accessed
  by step 3 then walks a stale rmap and dereferences a freed kvm_mmu_page.
  This includes dirty logging or MMU notifier invalidations (e.g., from
  MADV_DONTNEED).

The underlying issue is that KVM's walking of shadow PTEs assumes that
if a SPTE is present when KVM wants to install a non-leaf SPTE, then the
existing kvm_mmu_page must be for the correct gfn.  Because the only way
for the gfn to be wrong is if KVM messed up and failed to zap a SPTE...
which shouldn't happen, but *actually* only happens in response to a
guest write.

That bug dates back literally forever, as even the first version of KVM
assumes that the GFN matches and walks into the "wrong" shadow page.
However, that was only an imprecision until 2032a93d66fa ("KVM: MMU:
Don't allocate gfns page for direct mmu pages") came along.

Fix it by checking for a target gfn mismatch and zapping the existing
SPTE.  That way the old SP and rmap entries are gone, KVM installs
the rmap in the right location, and everyone is happy.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-46113?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46113?

Apply the vendor's patch.

## Is CVE-2026-46113 being exploited?

There is no known exploitation of CVE-2026-46113 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46113 and fix it if it is affected.

What it is: CVE-2026-46113 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46113 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-46113/ (Markdown: https://insights.sbomify.com/CVE-2026-46113/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46113
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46113
- OSV: https://osv.dev/vulnerability/CVE-2026-46113

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46113/
Summaries are generated and may contain mistakes; the official description above is the record.