CVE-2026-98921: Linux kernel · ovl: fix UAF in ovl_do_mkdir() debug print
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 28 Oct 2026, 02:28 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
Exploitation evidence
Disclosed: evidence found.
CVE published 23 Oct 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 for this vulnerability has been implemented by modifying the debug print logic in ovl_do_mkdir() to avoid use-after-free. Users should apply the updated Linux kernel versions that include this fix. No additional mitigations are required if the kernel is updated. If updating is not immediately possible, disabling CONFIG_OVERLAY_FS_DEBUG would avoid triggering the vulnerable debug code.
Description
CVE-2026-98921 is a use-after-free vulnerability in the Linux kernel's overlay filesystem (ovl) component. It occurs in the ovl_do_mkdir() function's debug print logic when CONFIG_OVERLAY_FS_DEBUG is enabled. The issue arises because the function prints a dentry pointer after a call to vfs_mkdir(), which may free or replace the dentry, leading to use-after-free. The fix involves printing the dentry before the call and only printing the result afterward.