CVE-2026-89926 Linux CVE debrief

Who should care

Linux kernel developers and administrators responsible for KVM implementations on s390 systems should be aware of this vulnerability and take steps to verify and apply patches to prevent large memory allocations. This includes reviewing system logs for potential memory allocation issues and restricting userspace access to the KVM implementation. Additionally, security teams and vulnerability management teams should be aware of the potential impact and plan

Why it matters

A vulnerability in the Linux kernel's KVM implementation for s390 allows userspace to trigger large memory allocations, potentially leading to memory allocation issues.

• Verify and apply patches to prevent large memory allocations
• Monitor system logs for potential memory allocation issues
• Restrict userspace access to the KVM implementation

Technical summary

The __import_wp_info() function in the Linux kernel's KVM implementation for s390 does not properly validate the length of user-supplied data, leading to potential memory allocation issues. This vulnerability can cause significant memory allocation problems, potentially leading to system instability or denial-of-service conditions. The vulnerability is resolved by using the validated value for memory allocation, ensuring that large allocations are properly handled. Affected systems include those running Linux kernels with KVM support enabled for s390.

Defensive priority

Verify and apply the patch to prevent large memory allocations.

Recommended defensive actions

• Verify the Linux kernel version and apply the patch if necessary
• Monitor system logs for potential memory allocation issues
• Restrict userspace access to the KVM implementation
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, but the scope of affected versions and potential impact require further verification. The Linux kernel's KVM implementation for s390 is vulnerable due to improper validation of user-supplied data in the __import_wp_info() function. This vulnerability can lead to large memory allocations, potentially causing system issues. Evidence from the CVE record and source item suggests that the vulnerability is resolved in updated Linux kernel versions.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.