CVE-2026-89921
Published Sep 16, 2026
Description
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Zero initialize data structures for inject_pfault_token __kvm_inject_pfault_token() only sets .type and .u.ext.ext_params2 of the on-stack struct kvm_s390_irq but the full ext substructure is copied into the cpu local variable on inject. ext_params and pad contain stale stack values. Interrupt delivery only uses ext_params2, so nothing leaks to the guest, but a host user can use the migration ioctls to get to the data. Fix by zero-initializing the irq struct. Do the same for the inti data structure.
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References
Frequently Asked Questions
What is CVE-2026-89921? +
In the Linux kernel, the following vulnerability has been resolved:
KVM: s390: Zero initialize data structures for inject_pfault_token
__kvm_inject_pfault_token() only sets .type and .u.ext.ext_params2 of
the on-stack struct kvm_s390_irq but the full ext substructure is copied
into the cpu local variable on inject. ext_params and pad contain stale
stack values.
Interrupt delivery only uses ext_params2, so nothing leaks to the guest,
but a host user can use the migration ioctls to get to the data.
Fix by zero-initializing the irq struct.
Do the same for the inti data structure.
How do I check if I'm vulnerable to CVE-2026-89921? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.