CVE-2026-89692: Linux kernel · nfsd: clear CALLBACK_RUNNING on failed delegation recall queue
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.5 High.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation 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 is available that properly clears the NFSD4_CALLBACK_RUNNING flag when the delegation recall queue attempt fails. Users should apply the updated Linux kernel versions that include this fix. No additional mitigation is required beyond applying the official patch.
Description
A vulnerability in the Linux kernel's NFS daemon (nfsd) related to delegation recall queue handling has been resolved. The issue involves the NFSD4_CALLBACK_RUNNING flag not being cleared properly when a delegation recall queue attempt fails, causing subsequent recall attempts to be skipped. This results in delegations never being broken, potentially causing conflicting opens or locks to stall. The fix clears the callback running flag when the queue fails to ensure proper delegation recall processing.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89692 (opens in a new tab)
- git.kernel.org/stable/c/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96 (opens in a new tab)
- git.kernel.org/stable/c/b137930ee52e3ef38915a3511d4c070463b63a32 (opens in a new tab)
- git.kernel.org/stable/c/cb2d0c4d1b3d301d042ed61365eaa8cb0141a254 (opens in a new tab)
- ubuntu.com/security/CVE-2026-89692 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89692 (opens in a new tab)
- git.kernel.org/linus/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96 (opens in a new tab)