CVE-2026-43331: Linux kernel · x86/kexec: Disable KCOV instrumentation after load_segments()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1066.69~22.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1066.69~22.04.1, 6.8.0-1070.78~22.04.1, 6.8.0-1068.75~22.04.1 +23
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
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 26.04 LTSlinux-nvidiapkg:deb/ubuntu/linux-nvidia?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– |
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 disables KCOV instrumentation for the affected kernel components to prevent kernel crashes. Users should apply the official Linux kernel updates that include this fix. Since a patch is available, updating to a fixed kernel version is the recommended remediation.
Description
A vulnerability in the Linux kernel's x86 kexec implementation causes kernel crashes when KCOV instrumentation is enabled. The issue occurs because the load_segments() function invalidates the GS base, which KCOV relies on for per-CPU data, leading to endless kernel crashes during instrumented code execution. This affects systems using CONFIG_KEXEC and CONFIG_KCOV simultaneously, primarily impacting crash dump collection workflows in fuzzing tools like syzkaller. The vulnerability does not affect 32-bit kernels as KCOV is unsupported there. A fix is available that disables KCOV instrumentation for the affected kernel components to prevent crashes.
References
- ubuntu.com/security/CVE-2026-43331 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-43331 (opens in a new tab)
- git.kernel.org/linus/917e3ad3321e75ca0223d5ccf26ceda116aa51e1 (opens in a new tab)
- git.kernel.org/stable/c/1e3e98596c2769721ade0418434852fb3af4849a (opens in a new tab)
- git.kernel.org/stable/c/917e3ad3321e75ca0223d5ccf26ceda116aa51e1 (opens in a new tab)
- git.kernel.org/stable/c/de05c66fab8847237a9ca216934e56d3ee837f08 (opens in a new tab)
- ubuntu.com/security/notices/USN-8903-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8905-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8906-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8904-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8903-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8905-2 (opens in a new tab)