CVE-2026-53345

What the bug is

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.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

virt/kvm/kvm_main.c

What this is

KERNEL VIRTUAL MACHINE (KVM)MAINTAINERS section matched on virt/kvm/* · kvm@vger.kernel.org · Supported

Show whether Debian builds this, per release

Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.

• bookworm, trixie, forky, sid?

?

not established - no Makefile entry for the affected file

Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS

Signals

Published

2026-07-01 (4 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.12%, higher than 1.7% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

virt/kvm

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
5.17	6.6.143	033d39e41fc3
5.17	6.12.94	66a8e7ddd901
5.17	6.18.36	343e95c8ecc4
5.17	7.0.13	99d7d43784ae
5.17	7.1	8618004d3e89