CVE-2026-72379: Linux kernel · fs: refuse O_TMPFILE creation with an unmapped fsuid or fsgid
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 4.8 Medium · fixed in 6.8.0-147.147 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-147.147, 6.8.0-1067.70, 7.0.0-1014.14~24.04.1 +25
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 15 Aug 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
Upgrade to a fixed release listed under Affected software.
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 patch is available and should be applied to affected Linux kernel versions to address this vulnerability. The fix adds a check in vfs_tmpfile() to refuse O_TMPFILE creation when the caller's fsuid or fsgid does not map into the filesystem, preventing invalid ownership tmpfiles. Users should update to patched kernel versions listed in the advisory. No additional mitigations are indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's handling of O_TMPFILE creation on idmapped mounts was resolved. The kernel did not verify that the caller's filesystem user ID (fsuid) and group ID (fsgid) mapped into the filesystem, allowing creation of tmpfiles with invalid ownership. This issue affects filesystems that support ID mapping and implement the tmpfile operation, including tmpfs, ext4, btrfs, xfs, f2fs, and overlayfs. The flaw could lead to tmpfiles owned by invalid user IDs, violating filesystem ownership guarantees. The vulnerability has been patched in affected Linux kernel versions.
References
- nvd.nist.gov/vuln/detail/CVE-2026-72379 (opens in a new tab)
- git.kernel.org/stable/c/47e434da476b5a8bcd1e6e52ab03c5ee7764ee78 (opens in a new tab)
- git.kernel.org/stable/c/503d0568a525b168d9aa5ca046ec72fc5477df84 (opens in a new tab)
- git.kernel.org/stable/c/539dce1144651f7976fa418e618b0b574bf15eeb (opens in a new tab)
- git.kernel.org/stable/c/a2038514e69371eb493083a6a897ed20fcbb8acb (opens in a new tab)
- git.kernel.org/stable/c/bac8fb0d60254846f3b56957435dcd870ae12948 (opens in a new tab)
- ubuntu.com/security/CVE-2026-72379 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-72379 (opens in a new tab)
- git.kernel.org/linus/539dce1144651f7976fa418e618b0b574bf15eeb (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8889-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8917-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8918-1 (opens in a new tab)