Linux Kernel up to 6.19.11 kick_cpus_irq_workfn deadlock

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.19.11 and classified as critical. Affected is the function kick_cpus_irq_workfn. The manipulation leads to deadlock. This vulnerability is documented as CVE-2026-43326. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.19.11. It has been rated as critical. This issue affects the function kick_cpus_irq_workfn. The manipulation with an unknown input leads to a deadlock vulnerability. Using CWE to declare the problem leads to CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait to balance callback SCX_KICK_WAIT busy-waits in kick_cpus_irq_workfn() using smp_cond_load_acquire() until the target CPU's kick_sync advances. Because the irq_work runs in hardirq context, the waiting CPU cannot reschedule and its own kick_sync never advances. If multiple CPUs form a wait cycle, all CPUs deadlock. Replace the busy-wait in kick_cpus_irq_workfn() with resched_curr() to force the CPU through do_pick_task_scx(), which queues a balance callback to perform the wait. The balance callback drops the rq lock and enables IRQs following the sched_core_balance() pattern, so the CPU can process IPIs while waiting. The local CPU's kick_sync is advanced on entry to do_pick_task_scx() and continuously during the wait, ensuring any CPU that starts waiting for us sees the advancement and cannot form cyclic dependencies.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-43326 since 05/01/2026. The exploitation is known to be difficult. Technical details are known, but no exploit is available.

Upgrading to version 6.19.12 eliminates this vulnerability. Applying the patch c3a7903f65cf4c7fb0477eb0f8b94f326a47fe54/415cb193bb9736f0e830286c72a6fa8eb2a9cc5c is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1454). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Google Container-Optimized OS
• Debian Linux
• Red Hat Enterprise Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Microsoft Azure Linux
• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8
• 6.19.9
• 6.19.10
• 6.19.11

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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