# CVE-2026-43326: linux: In the Linux kernel, the following vulnerability has been resolved:  sched_ext: Fix SCX_KICK_WAIT deadlock by deferri...

CVE-2026-43326 is fixed in linux on 1 platform by DEBIAN-CVE-2026-43326 (version 6.19.12-1), released May 15, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-43326
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0008
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 8, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.19.12-1 | [DEBIAN-CVE-2026-43326](https://patchblox.com/security/data/fix/linux/debian-cve-2026-43326.md) | May 15, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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