CVE-2026-89701: Linux kernel · nfsd: validate nseconds in TIME_DELEG decode paths
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 10% 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 implemented that adds proper range checks for the nseconds field in the TIME_DELEG decode paths within the Linux kernel source files nfs4xdr.c and nfs4callback.c. Users should apply the official kernel updates that include this patch to remediate the vulnerability. Since this is a kernel-level issue, upgrading to patched kernel versions is the recommended mitigation.
Description
A vulnerability in the Linux kernel's NFS server (nfsd) component was resolved involving improper validation of nanoseconds in TIME_DELEG decode paths. The issue allowed a raw uint32_t nseconds value to be stored directly into the tv_nsec field without ensuring it was less than NSEC_PER_SEC, unlike legacy code that performed this check. This flaw could allow malformed timespec values to propagate through notify_change() to disk. The fix added range checks in the affected decode paths.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89701 (opens in a new tab)
- git.kernel.org/stable/c/0f4a767340fad392bd656115b8752005518c9065 (opens in a new tab)
- git.kernel.org/stable/c/5eb489831a9fd4754f4baf26e6989efb66ce104c (opens in a new tab)
- git.kernel.org/stable/c/7e7b93da7fa2e77f977096251899d1410986adf6 (opens in a new tab)
- ubuntu.com/security/CVE-2026-89701 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89701 (opens in a new tab)
- git.kernel.org/linus/0f4a767340fad392bd656115b8752005518c9065 (opens in a new tab)