CVE-2026-43392 | sched_ext: Fix starvation of scx_enable() under fair-class saturation

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_enable_cmd containing the kthread_work, then synchronously waits for completion. The workfn runs on a different kthread from sch->helper (which runs disable_work), so it can safely flush disable_work on the error path without deadlock.

Published: 2026-05-08 Last update: 2026-06-17 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-43392 is rated Low Risk (23.1/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.13%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-43392

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.02% 0.13% +0.11%
2 2026-05-09 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-43392

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 3.6 [email protected]

Weakness enumeration for CVE-2026-43392

GitHub Security Advisory for CVE-2026-43392

GHSA-vww6-hvwf-mv33 · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix starvation of...

OS Trackers for CVE-2026-43392

vendor priority summary link
debian unimportant CVE-2026-43392 unimportant priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-43392
redhat — — https://access.redhat.com/security/cve/CVE-2026-43392
suse medium CVE-2026-43392 severity moderate: SUSE including 20 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 184 product×package rows across 36 product lines (SUSE Linux Enterprise High Availability Extension 15 SP7, SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, … (36 product lines)): Known Not Affected 184. https://www.suse.com/security/cve/CVE-2026-43392/
ubuntu medium CVE-2026-43392 medium priority: Ubuntu including 161 source packages (linux, linux-allwinner-5.19, …), 1449 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 1048, ignored 169, not-affected 122, released 87, needed 22, needs-triage 1. https://ubuntu.com/security/CVE-2026-43392

Affected software / configurations for CVE-2026-43392

Vendor Product Version Raw CPE
linux linux_kernel >= 6.12.1, < 6.12.78 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.18.20 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.19, < 6.19.9 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:-:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc2:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc3:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc4:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc5:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc6:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc7:*:*:*:*:*:*
linux linux_kernel 7.0 cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
linux linux_kernel 7.0 cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*

References for CVE-2026-43392

cvelogic Threat Intelligence