CVE-2026-98418 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, system administrators responsible for Linux kernel updates, and security teams should be aware of this issue. They should review and apply the patch to exclude blocked proxy donors from the warning. Additionally, they should monitor system logs for potential false positives and verify system configurations to ensure migration-disabled tasks are properly handled.

Why it matters

A false migration warning issue in the Linux kernel's sched/core could lead to unnecessary warnings and potential system instability. Defenders should verify Linux kernel configurations, monitor system logs, and review and apply the patch to mitigate the issue.

• Defenders should verify Linux kernel configurations to ensure migration-disabled tasks are properly handled
• System administrators should monitor system logs for potential false positives
• Linux kernel developers should review and apply the patch to exclude blocked proxy donors from the warning

Technical summary

The Linux kernel's sched/core has a false migration warning issue. The warning is triggered when a blocked donor's scheduling context is moved to the lock owner's CPU even when the donor is migration-disabled. The issue has been resolved by excluding blocked proxy donors from the warning. This occurs because proxy execution can move a blocked donor's scheduling context to the lock owner's CPU, even when the donor is migration-disabled. The donor does not execute there, and its original execution CPU remains recorded in wake_cpu. set_task_cpu() warns unconditionally for migration-disabled tasks, leading to a false positive.

Defensive priority

Low

Recommended defensive actions

• Review and apply the patch to exclude blocked proxy donors from the warning
• Monitor system logs for potential false positives
• Verify system configurations to ensure migration-disabled tasks are properly handled
• 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 issue is described in the Linux kernel's sched/core. The CVE Program record and NVD vulnerability detail provide additional information. The problem is caused by proxy execution moving a blocked donor's scheduling context to the lock owner's CPU even when the donor is migration-disabled. The donor does not execute there, and its original execution CPU remains recorded in wake_cpu. set_task_cpu() warns unconditionally for migration-disabled tasks, leading to a false positive. This can occur when creating a mutex owner on CPU1 and a

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.