CVE-2026-68329 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux kernel versions prior to the fixed commits should assess exposure and prioritize patching. Linux kernel developers and maintainers should review and test patches. Linux distribution vendors should integrate patches into their distributions and notify users. Users of Linux kernel versions prior to the fixed commits should assess their exposure and prioritize patching to

Why it matters

A logical race condition vulnerability exists in the Linux kernel's iommu/amd implementation. The iommu_completion_wait() function returns early when it reads the need_sync flag as false, potentially leading to use-after-free scenarios. Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux kernel versions prior to the fixed commits should assess exposure and prioritize patching.

• Potential use-after-free scenarios may lead to system crashes or code execution.
• Successful exploitation requires local access and low privileges.
• Defenders should verify system integrity and patch vulnerable versions.

Technical summary

The iommu_completion_wait() function in the Linux kernel's iommu/amd implementation has a logical race condition. The function reads the need_sync flag locklessly and returns early when it is false, potentially leading to use-after-free scenarios. The vulnerability is caused by a logical race condition in the iommu_completion_wait() function. The need_sync flag is shared among all domains and devices behind an IOMMU. When a command is queued with sync == true, need_sync is set to true. It is cleared when a completion-wait (CWAIT) command is queued. However, a cleared need_sync only indicates that a covering CWAIT has been queued, not that all previously queued commands have completed in hardware. This can lead

Defensive priority

High

Recommended defensive actions

• Review Linux kernel versions and assess exposure based on the provided affected versions.
• Prioritize patching to the fixed commits: ab7faf5a172ebfdc423ebb3eea4d472740de82f9, 93494bd446396c257fb589f59894577e96e406e2, d053eb7e09e10cbdca3fca8b35c1017d438091b2, 02f8cefa2ad95ea3754f0cfd6fbae7f866202ccb, 1e75a8255f
• 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.
• 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.

Evidence notes

The vulnerability is caused by a logical race condition in the iommu_completion_wait() function. The need_sync flag is shared among all domains and devices behind an IOMMU. When a command is queued with sync == true, need_sync is set to true. It is cleared when a completion-wait (CWAIT) command is queued. However, a cleared need_sync only indicates that a covering CWAIT has been queued, not that all previously queued commands have completed in hardware.

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.