CVE-2026-43392

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

sched_ext: Fix starvation of scx_enable() under fair-class saturation

During scx_enable(), the READY -> ENABLED task switching loop changes the

calling thread's sched_class from fair to ext. Since fair has higher

priority than ext, saturating fair-class workloads can indefinitely starve

the enable thread, hanging the system. This was introduced when the enable

path switched from preempt_disable() to scx_bypass() which doesn't protect

against fair-class starvation. Note that the original preempt_disable()

protection wasn't complete either - in partial switch modes, the calling

thread could still be starved after preempt_enable() as it may have been

switched to ext class.

Fix it by offloading the enable body to a dedicated system-wide RT

(SCHED_FIFO) kthread which cannot be starved by either fair or ext class

tasks. scx_enable() lazily creates the kthread on first use and passes the

ops pointer through a struct scx_en

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References