CVE-2026-89921: Linux kernel · KVM: s390: Zero initialize data structures for inject_pfault_token
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 12:55 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 16 Sep 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 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther 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 zero-initializes the affected data structures in the Linux kernel KVM s390 code. Users should apply the official kernel updates that address this issue. Since this is a kernel-level vulnerability, updating to patched kernel versions is the recommended mitigation.
Description
A vulnerability in the Linux kernel's KVM s390 subsystem involves uninitialized data structures in the inject_pfault_token function. Specifically, only parts of the kvm_s390_irq struct are initialized, leaving other fields with stale stack data. While interrupt delivery uses only initialized fields, a host user can exploit migration ioctls to access this residual data. The issue is fixed by zero-initializing the affected data structures.
References
- ubuntu.com/security/CVE-2026-89921 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89921 (opens in a new tab)
- git.kernel.org/linus/4e2c7f7cbc27418f9a290399b986c1b85ff93b90 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-89921 (opens in a new tab)
- git.kernel.org/stable/c/134f235e0e8de54611a72d3cc3f63e5f31246baa (opens in a new tab)
- git.kernel.org/stable/c/4e2c7f7cbc27418f9a290399b986c1b85ff93b90 (opens in a new tab)
- git.kernel.org/stable/c/9b046de62b8098af6e2ba820b125ec9dc5f162c8 (opens in a new tab)
- git.kernel.org/stable/c/b8abc760fa18a389319d977834a30550b3ec18e8 (opens in a new tab)