CVE-2026-43392: Linux kernel · sched_ext: Fix starvation of scx_enable() under fair-class saturation
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 8 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available that offloads the enable operation to a dedicated real-time kernel thread to prevent starvation. Users should apply the updated Linux kernel versions that include this fix. Since this is a kernel-level issue, upgrading to patched kernel versions is the recommended remediation.
Description
A vulnerability in the Linux kernel scheduler (sched_ext) could cause system hangs due to starvation of the scx_enable() function under fair-class saturation. The issue arises because the READY -> ENABLED task switching loop changes the calling thread's scheduling class from fair to ext, and since fair has higher priority, saturating fair-class workloads can indefinitely starve the enable thread. This was fixed by offloading the enable operation to a dedicated real-time kthread that cannot be starved by fair or ext class tasks.
References
- ubuntu.com/security/CVE-2026-43392 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-43392 (opens in a new tab)
- git.kernel.org/linus/b06ccbabe2506fd70b9167a644978b049150224a (opens in a new tab)
- git.kernel.org/stable/c/05ab9ec5dc24f234e0a2fecf3e6ff937c68f7d81 (opens in a new tab)
- git.kernel.org/stable/c/b06ccbabe2506fd70b9167a644978b049150224a (opens in a new tab)
- git.kernel.org/stable/c/c44198f25fdfecc0ec0fe366bf8a47fe17d8e229 (opens in a new tab)
- git.kernel.org/stable/c/e0b14bf06393be137d3efb6a3b7cd5b4b9810a6b (opens in a new tab)