In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Ignore -EBUSY when checking nested events from vcpu_block()
Ignore -EBUSY when checking nested events after exiting a blocking state
while L2 is active, as exiting to userspace will generate a spurious
userspace exit, usually with KVM_EXIT_UNKNOWN, and likely lead to the VM's
demise. Continuing with the wakeup isn't perfect either, as *something*
has gone sideways if a vCPU is awakened in L2 with an injected event (or
worse, a nested run pending), but continuing on gives the VM a decent
chance of surviving without any major side effects.
As explained in the Fixes commits, it _should_ be impossible for a vCPU to
be put into a blocking state with an already-injected event (exception,
IRQ, or NMI). Unfortunately, userspace can stuff MP_STATE and/or injected
events, and thus put the vCPU into what should be an impossible state.
Don't bother trying to preserve the WARN, e.g. with an anti-syzkaller
Kconfig, as WARNs can (hopefully) be added in paths where _KVM_ would be
violating x86 architecture, e.g. by WARNing if KVM attempts to inject an
exception or interrupt while the vCPU isn't running.
References
Configurations
Configuration 1 (hide)
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History
11 Nov 2026, 23:10
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Information
Published : 2026-05-06 12:16
Updated : 2026-11-11 23:10
NVD link : CVE-2026-43265
Mitre link : CVE-2026-43265
CVE.ORG link : CVE-2026-43265
JSON object : View
Products Affected
linux
- linux_kernel
CWE