# CVE-2026-53345: KVM: Don't WARN if memory is dirtied without a vCPU when the VM is dying

> A logic error in KVM triggers a kernel warning when SEV-ES VMs are destroyed, potentially causing a denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 1 Jul 2026
- **Updated:** 10 Jul 2026
- **Also known as:** AZL-91616, BELL-CVE-2026-53345, DEBIAN-CVE-2026-53345, GHSA-m28w-5q4v-5m48, ROOT-OS-DEBIAN-11-CVE-2026-53345, ROOT-OS-DEBIAN-12-CVE-2026-53345, ROOT-OS-UBUNTU-2204-CVE-2026-53345, ROOT-OS-UBUNTU-2404-CVE-2026-53345, UBUNTU-CVE-2026-53345

## What is CVE-2026-53345?

CVE-2026-53345 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Jul 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: Don't WARN if memory is dirtied without a vCPU when the VM is dying

When marking a page dirty, complain about not having a running/loaded vCPU
if and only if the VM is still alive, i.e. its refcount is non-zero.  This
will allow fixing a memory leak for x86 SEV-ES guests without hitting what
is effectively a false positive on the WARN.

For some SEV-ES VM-Exits, KVM keeps a writable mapping of a guest page
across an exit to userspace, and typically unmaps the page on the next
KVM_RUN.  But if userspace never calls KVM_RUN after such an exit, then KVM
needs to unmap the page when the vCPU is destroyed, which in turn triggers
the WARN about not having a running vCPU.

Alternatively, SEV-ES could temporarily load the vCPU to suppress the WARN,
as is done in nested_vmx_free_vcpu() (but for completely unrelated reasons;
suppressing WARN from nested_put_vmcs12_pages() is pure happenstance).  But
loading a vCPU during destruction is gross (ideally nVMX code would be
cleaned up), risks complicating the SEV-ES code (KVM would need to ensure
the temporarily load()+put() only runs when the vCPU isn't already loaded),
and is ultimately pointless.

The motivation for the WARN is to guard against KVM dirtying guest memory
without pushing the corresponding GFN to the active vCPU's dirty ring, e.g.
to ensure userspace doesn't miss a dirty page.  But for the VM's refcount
to reach zero, there can't be _any_ userspace mappings to the dirty ring,
as mapping the dirty ring requires doing mmap() on the vCPU FD.  I.e. if
userspace had a valid mapping for the dirty ring, then the vCPU file and
thus the owning VM would still be alive.  And so since userspace can't
possibly reach the dirty ring, whether or not KVM technically "misses" a
push to the dirty ring is irrelevant.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2026-53345?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53345?

Apply the vendor's patch.

## Is CVE-2026-53345 being exploited?

There is no known exploitation of CVE-2026-53345 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-2026-53345 and fix it if it is affected.

What it is: CVE-2026-53345 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Jul 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-2026-53345 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-2026-53345/ (Markdown: https://insights.sbomify.com/CVE-2026-53345/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53345
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53345
- OSV: https://osv.dev/vulnerability/CVE-2026-53345

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53345/
Summaries are generated and may contain mistakes; the official description above is the record.