CVE-2026-53345 is a vulnerability in Linux Kernel
Published on July 1, 2026
KVM: Don't WARN if memory is dirtied without a vCPU when the VM is dying
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.
Products Associated with CVE-2026-53345
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Affected Versions
Linux:- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 033d39e41fc30f484f4e4f37fb4cd76b12cbb18e is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 66a8e7ddd901023c89a2733494d827eca3f9c1b0 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 343e95c8ecc40e0738975ef4ee24c0c35e800e6b is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 99d7d43784ae3235026581e9bf892c036e04c8e6 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 8618004d3e897c0f1b71d9a9ab860461289bb89a is affected.
- Before 6.6.143 is affected.
- Before 6.12.94 is affected.
- Before 6.18.36 is affected.
- Before 7.0.13 is affected.
- Version 6.6.143, <= 6.6.* is unaffected.
- Version 6.12.94, <= 6.12.* is unaffected.
- Version 6.18.36, <= 6.18.* is unaffected.
- Version 7.0.13, <= 7.0.* is unaffected.
- Version 7.1, <= * is unaffected.