CVE-2026-89681: Linux kernel · nfsd: fix layout fence worker double-reference race
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical.
Data as of 12 Nov 2026, 20:25 UTC
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 12 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinux-aws-6.14pkg:deb/ubuntu/linux-aws-6.14?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-aws-6.17pkg:deb/ubuntu/linux-aws-6.17?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.14pkg:deb/ubuntu/linux-azure-6.14?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.17pkg:deb/ubuntu/linux-azure-6.17?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-fde-6.14pkg:deb/ubuntu/linux-azure-fde-6.14?arch=source&distro=nobleOther 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 for this vulnerability is available and should be applied promptly. The patch replaces the racy delayed_work_pending() check with an atomic boolean flag and adjusts the worker scheduling to prevent double references and memory leaks. Users should update affected Linux kernel versions to the fixed releases or later. No alternative mitigations or workarounds are indicated.
Description
CVE-2026-89681 is a critical vulnerability in the Linux kernel's nfsd component involving a race condition that causes a double-reference of a layout fence worker. This flaw leads to a reference count leak, resulting in a memory leak of the layout stateid. The issue arises from a race in the workqueue handling, where a delayed work check can incorrectly indicate no pending work, allowing duplicate references and scheduling of redundant workers. The vulnerability has been fixed by replacing the racy check with an atomic boolean flag and adjusting the worker scheduling logic.
References
- ubuntu.com/security/CVE-2026-89681 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89681 (opens in a new tab)
- git.kernel.org/linus/8580571227451384399b3fa53fcde19848c48e5a (opens in a new tab)
- git.kernel.org/stable/c/8580571227451384399b3fa53fcde19848c48e5a (opens in a new tab)
- git.kernel.org/stable/c/a278d361e0e8f242211891193d56483a7a9f47a8 (opens in a new tab)