CVE-2026-43402: Linux kernel · kthread: consolidate kthread exit paths to prevent use-after-free
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 6.17.0-1019.19~24.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.17.0-1019.19~24.04.1, 6.17.0-1020.22~24.04.1, 6.17.0-40.40~24.04.1 +11
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@7.0.0-1008.8?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-40.40?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1020.20?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1020.22?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 and has been released in Linux kernel versions 6.17.0-1019.19 and later, including various patched builds for Ubuntu 24.04 LTS and other distributions. Users should update their Linux kernel to these fixed versions and reboot to apply the changes. Due to ABI changes, recompilation and reinstallation of third-party kernel modules may be required. Follow vendor advisories such as Ubuntu Security Notice USN-8490-1 for detailed update instructions.
Description
A use-after-free vulnerability in the Linux kernel's kernel thread (kthread) exit paths was resolved by consolidating all kthread exit paths to ensure proper cleanup. The flaw involved memory corruption due to missed cleanup of affinity_node when a kthread exited via make_task_dead(), leading to potential corruption of function pointers. This vulnerability affects multiple Linux kernel versions prior to 6.17.0-1019 and related builds. The issue was fixed by restructuring the exit path logic to guarantee kthread-specific cleanup regardless of exit method.
References
- ubuntu.com/security/CVE-2026-43402 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-43402 (opens in a new tab)
- git.kernel.org/linus/28aaa9c39945b7925a1cc1d513c8f21ed38f5e4f (opens in a new tab)
- git.kernel.org/stable/c/28aaa9c39945b7925a1cc1d513c8f21ed38f5e4f (opens in a new tab)
- git.kernel.org/stable/c/4729c7b00a347fd37d0cbc265b85f2884c3e06b6 (opens in a new tab)
- git.kernel.org/stable/c/5a591d7a5e48d30100943940a30a6ab41b15c672 (opens in a new tab)
- ubuntu.com/security/notices/USN-8490-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8491-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8508-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8490-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8545-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8546-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8604-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8605-1 (opens in a new tab)