CVE-2026-90243 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux-based systems should verify system configurations, monitor system logs, and apply updates and patches. They should also review the patch notes and apply updates accordingly. Additionally, they should check relevant monitoring, detection, and logs for exposed assets that need extra review.

Why it matters

A vulnerability in the Linux kernel's iommu/vt-d has been resolved. The issue involves the improper teardown of copied context entries, which could lead to unpredictable behavior or spurious faults. Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux-based systems should verify system configurations, monitor system logs, and apply updates and patches.

• Verify IOMMU settings and system configurations to prevent potential issues
• Monitor system logs for unusual activity
• Apply Linux kernel updates and patches

Technical summary

The Linux kernel's iommu/vt-d has a vulnerability in the teardown of copied context entries. The Present bit is not cleared before tearing down the entry, which could lead to unpredictable behavior or spurious faults. The fix involves clearing the Present bit before tearing down the entry and performing invalidations, as per the VT-d spec. This change ensures that hardware cannot fetch torn entries, preventing potential issues. The fix also includes flushing the entry out to the IOMMU and performing invalidations to ensure visibility to hardware.

Defensive priority

High

Recommended defensive actions

• Review Linux kernel patch notes and apply updates
• Verify system configurations and validate IOMMU settings
• Monitor system logs for unusual activity
• 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
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability. The Linux kernel patch notes and Git commit hashes are also available. The fix involves clearing the Present bit before tearing down the copied context entry and performing invalidations, as described in the VT-d spec, Section 6.5.3.3. The change prevents unpredictable behavior or spurious faults by ensuring hardware cannot fetch torn entries.

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.