CVE-2026-89683: Linux kernel · nfsd: fix dentry ref leak on V4ROOT export filehandle lookup
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 14:05 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% 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
Until a fix is confirmed, avoid processing untrusted NFSv3 filehandles targeting V4ROOT exports or apply any vendor recommended mitigations once available.
Description
A vulnerability in the Linux kernel's NFS daemon (nfsd) causes a dentry reference leak during V4ROOT export filehandle lookup. This occurs because the function nfsd_set_fh_dentry() fails to properly release a dentry reference when handling certain NFSv3 filehandles targeting a V4ROOT export's fsid. The leak happens on every request with a crafted filehandle.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89683 (opens in a new tab)
- git.kernel.org/stable/c/11db8df188b34bdb8c6a3a0bf438e5fc8cd75aca (opens in a new tab)
- git.kernel.org/stable/c/6247023fbbec1325029f2d5f2a7cdc0f9f9ea15a (opens in a new tab)
- git.kernel.org/stable/c/c1ae0f973bcba5730871e35976a0ab6878fdac34 (opens in a new tab)
- git.kernel.org/stable/c/d493cf57f4c4dae5396cd6ad41e5c209d0615a81 (opens in a new tab)
- ubuntu.com/security/CVE-2026-89683 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89683 (opens in a new tab)
- git.kernel.org/linus/6247023fbbec1325029f2d5f2a7cdc0f9f9ea15a (opens in a new tab)