CVE-2026-89765: Linux kernel · timers/itimer: Zero-init old itimerval before copy to userspace
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 13:47 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 11 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 has been applied to the Linux kernel source to zero-initialize the __kernel_old_itimerval structure before copying it to userspace. Users should update to patched kernel versions that include this fix. Since this is a kernel-level vulnerability, applying official kernel updates from the respective Linux distribution vendors is the recommended remediation. No additional mitigation is indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's timers/itimer subsystem was resolved by zero-initializing the old itimerval structure before copying it to userspace. On native sparc64 architectures, the __kernel_old_timeval struct contains padding bytes due to size differences in its fields. Previously, uninitialized padding could be exposed to userspace via getitimer(), potentially leaking kernel stack data. The fix ensures the entire structure is zeroed before field assignment, preventing leakage of uninitialized memory.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89765 (opens in a new tab)
- git.kernel.org/stable/c/00ef529a5402f41eb1d227916437e237450719f9 (opens in a new tab)
- git.kernel.org/stable/c/18c7d85864e554adc8fad1e8d2e9d2cb6c3911c8 (opens in a new tab)
- git.kernel.org/stable/c/2bf5e8f7c9bf4ad3be343a9a6e3e50a34264d25e (opens in a new tab)
- git.kernel.org/stable/c/4c66719dd1e4023c5e3f7d050f1bbefec3dfbeb4 (opens in a new tab)
- msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-89765.json (opens in a new tab)
- support.microsoft.com/lifecycle (opens in a new tab)
- first.org/cvss (opens in a new tab)
- ubuntu.com/security/CVE-2026-89765 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89765 (opens in a new tab)
- git.kernel.org/linus/18c7d85864e554adc8fad1e8d2e9d2cb6c3911c8 (opens in a new tab)