CVE-2026-89767: Linux kernel · ovl: fix double end_creating() on the casefold-mismatch path
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 28 Oct 2026, 01:04 UTC
CVSS:3.1/AV:L/AC:L/PR:L/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
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 removes the redundant end_creating() call on the casefold-mismatch path in ovl_create_real(), ensuring proper cleanup without double unlocking or double dput. Users should apply the updated Linux kernel versions that include this fix. No additional mitigations are necessary beyond applying the official patch.
Description
CVE-2026-89767 is a vulnerability in the Linux kernel's overlay filesystem (ovl) where a double call to end_creating() occurs on a casefold-mismatch error path during directory creation. This double call leads to unlocking a lock twice and dropping a reference twice, causing the parent directory's lock to be released improperly and subsequent directory creations under that parent to hang indefinitely. The flaw is reachable by unprivileged users and affects certain Linux kernel versions. The issue arises from incorrect handling of casefold consistency checks and improper cleanup logic in ovl_create_real().
References
- ubuntu.com/security/CVE-2026-89767 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89767 (opens in a new tab)
- git.kernel.org/linus/077ab8985ee278c3d8618182d335b0f0cd919e16 (opens in a new tab)
- git.kernel.org/stable/c/077ab8985ee278c3d8618182d335b0f0cd919e16 (opens in a new tab)
- git.kernel.org/stable/c/2fa220bc0f84597cb6de665e5b5021c5901ddf00 (opens in a new tab)
- git.kernel.org/stable/c/b1aa8ab78a8e87aee9e306971465408e059f839a (opens in a new tab)