CVE-2026-43265: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux Kernel: from 6.1, before 6.1.167 (fixed in 6.1.167); from 6.2, before 6.6.130 (fixed in 6.6.130); from 6.7, before 6.12.77 (fixed in 6.12.77); from 6.13, before 6.18.17 (fixed in 6.18.17); from 6.19, before 6.19.6 (fixed in 6.19.6)

Published 2026-05-06. Last modified 2026-06-17.