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.
Affected versions
Linux kernel versions
3.19
and later are affected. Fixed in
6.12.112,
6.18.52,
7.2.5,
7.3-rc1
and their respective stable series.
References
4 totalFrequently asked questions
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What is CVE-2026-89921?
CVE-2026-89921 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 3.19 onward and has been patched in 6.12.112, 6.18.52, 7.2.5 and others. CVE-2026-89921 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-89921?
Yes. CVE-2026-89921 has been patched. Fixed versions include 6.12.112, 6.18.52, 7.2.5 and others. If you are running Linux kernel 3.19 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-89921 actively exploited?
No. CVE-2026-89921 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.