CVE-2026-74439 Linux CVE debrief

Who should care

Linux kernel maintainers, users, and administrators should be aware of this vulnerability and take necessary actions to patch and mitigate potential risks. This includes reviewing and updating Linux kernel configurations to ensure iommu/vt-d is properly configured and monitoring system logs for potential faults or errors related to iommu/vt-d. Additionally, operators, platform administrators, vulnerability management teams, and security teams should assess the impact on their systems and prioritize patching to prevent potential unpredictable behavior or spurious faults. Affected product deployments should be identified in managed environments, and owners should be assigned for follow-up. Compensating controls should be reviewed for exposed systems while remediation is scheduled and verified. Monitoring, detection, and logs should be checked for exposed assets that need extra review. Exceptions should be tracked, and remediated assets should be retested before closing the item, with evidence documented. Asset inventory and source tracking can help in managing the remediation process effectively. Rollback/change windows should be considered if immediate patching is not feasible. The CVE record and official advisory should be reviewed to validate affected scope, severity, and vendor guidance. This vulnerability affects Linux kernel deployments, particularly those using iommu/vt-d, and requires prompt attention to prevent potential security issues. Security teams should track the remediation status and verify that patches have been applied correctly. The vulnerability management process should include verification of patch deployment and assessment of compensating controls. The affected systems should be prioritized based on their criticality and potential impact on the organization. The remediation process should be coordinated with relevant stakeholders, including IT operations, security teams, and system administrators. The vulnerability should be monitored for potential exploitation attempts, and incident response plans should be in place in case of a security incident. The Linux kernel community and distributions should be engaged to ensure that the patch is ,

Technical summary

The Linux kernel vulnerability in iommu/vt-d allows for unpredictable behavior or spurious faults due to improper teardown of scalable-mode context entries. The fix involves clearing the Present bit before zeroing the entry and performing context-cache invalidation. This ensures that the hardware does not fetch a torn entry with some fields already zeroed while the Present bit is still set. The vulnerability was addressed by aligning the device_pasid_table_teardown() function with the guidance provided in the VT-d spec, Section 6.5.3.3.

Defensive priority

Linux kernel maintainers and users should prioritize patching this vulnerability to prevent potential unpredictable behavior or spurious faults.

Recommended defensive actions

• Apply the patch to clear the Present bit before tearing down the scalable-mode context entry
• Review and update Linux kernel configurations to ensure iommu/vt-d is properly configured
• Monitor system logs for potential faults or errors related to iommu/vt-d
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The Linux kernel vulnerability was resolved by clearing the Present bit before tearing down the scalable-mode context entry. The issue arises from the device_pasid_table_teardown() function zeroing the 128-bit scalable-mode context entry with context_clear_entry() while the Present bit is still set, creating a window for unpredictable behavior or spurious faults.

Official resources