Linux KernelOperating system · Linux
CVE-2026-53345
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThis is a code-quality fix in Linux KVM rather than a traditional security vulnerability. The issue is a false-positive WARN that triggers when KVM unmaps a guest page during vCPU destruction for SEV-ES VMs, even though the VM is dying (refcount=0) and userspace cannot possibly access the dirty ring. The fix adds a check to only WARN if the VM is still alive.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
>= 5.17, < 6.6.143>= 6.7, < 6.12.94>= 6.13, < 6.18.36>= 6.19, < 7.0.13= 7.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check kernel versionRun `uname -r` or `cat /proc/version` to get the running kernel versionAffected if The kernel version falls within any of these ranges: >= 5.17 and < 6.6.143, >= 6.7 and < 6.12.94, >= 6.13 and < 6.18.36, >= 6.19 and < 7.0.13, or equals 7.1
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Verify KVM with SEV-ES is in useCheck if the system is running SEV-ES virtual machines. Look for SEV-ES active VMs using `ls /sys/firmware/sev` or check kvm_intel/sev module parameters with `cat /sys/module/kvm_intel/parameters/sev_es`Affected if SEV-ES is enabled and actively used with KVM on the system (the false-positive WARN only triggers in this configuration)
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Look for the false-positive WARN in kernel logsSearch kernel logs using `dmesg` or check /var/log/kern.log for messages containing 'WARN' related to KVM page unmap during vCPU destruction, particularly entries mentioning 'refcount' or 'dirty ring' in the context of SEV-ES VM teardownAffected if These WARN messages appear in logs during SEV-ES vCPU destruction (indicates the false-positive is occurring)
You are affected if running a kernel version in the affected ranges AND using SEV-ES VMs with KVM, with the false-positive WARN appearing in kernel logs during vCPU destruction.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped6.6.1436.12.946.18.36
Apply the upstream Linux kernel patch which adds a refcount check before triggering the WARN. This is a low-priority kernel update for systems running SEV-ES VMs with KVM.
Upgrade to kernel 6.6.143, 6.12.94, 6.18.36, or 7.0.13 (whichever corresponds to your stable branch)
- Identify the currently running kernel version using `uname -r`
- Determine which version range your current kernel falls into based on the affected versions: >= 5.17 and < 6.6.143, >= 6.7 and < 6.12.94, >= 6.13 and < 6.18.36, or >= 6.19 and < 7.0.13
- Obtain and apply the kernel patch from the referenced git.kernel.org commit that addresses the KVM memory leak (the patch modifies the dirty page tracking logic to check VM refcount before warning)
- Alternatively, upgrade the kernel to a fixed release: 6.6.143, 6.12.94, 6.18.36, or 7.0.13 depending on which stable branch you are on
- Reboot the system to load the patched kernel
- Verify the fix is applied by checking that the false positive WARN no longer appears in kernel logs when destroying SEV-ES VM vCPUs
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Linux Kernel
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-53345 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-53345 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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