CVE-2026-89745: Linux kernel · debugfs: Fix lockdown check for mmap_prepare
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 28 Oct 2026, 01:01 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
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.
Description
In the Linux kernel, the following vulnerability has been resolved: debugfs: Fix lockdown check for mmap_prepare Commit 651fdda8406d ("relay: update relay to use mmap_prepare") changed the `mmap` file operation to `mmap_prepare` for relayfs, but the lockdown check in debugfs was not updated accordingly. This prevents debugfs from being locked down when the kernel is in integrity mode if a file uses `mmap_prepare` but not `mmap`. Since the conversion to `mmap_prepare` across the kernel is not yet complete, update the lockdown check to look for both `mmap` and `mmap_prepare` to ensure comprehensive coverage.
References
- ubuntu.com/security/CVE-2026-89745 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89745 (opens in a new tab)
- git.kernel.org/linus/f81808de37338aac8e167f99bfae647b1b835c70 (opens in a new tab)
- git.kernel.org/stable/c/e7f6a6b5741d16fdac7adaecbe0fa52ae756f208 (opens in a new tab)
- git.kernel.org/stable/c/f81808de37338aac8e167f99bfae647b1b835c70 (opens in a new tab)