CVE-2026-53397: Linux kernel · nfsd: fix posix_acl leak on SETACL decode failure
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.5 High · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +43
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 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. The fix adds proper cleanup of allocated ACL structures on all code paths, preventing the memory leak. Users should update their Linux kernel packages to the fixed versions as provided by their vendor. No additional mitigation is required beyond applying the official update.
Description
A vulnerability in the Linux kernel's NFS server daemon (nfsd) caused a memory leak of posix_acl structures when decoding SETACL requests failed. This leak occurs because the cleanup function was not called on decode failure, leaving allocated ACLs dangling for the server's lifetime. The issue has been fixed by adding proper release functions that run on all code paths, including decode failures.
References
- nvd.nist.gov/vuln/detail/CVE-2026-53397 (opens in a new tab)
- git.kernel.org/stable/c/0853ac544c590880d797b04daa33fcb72b6be0e1 (opens in a new tab)
- git.kernel.org/stable/c/136b416593f1349cf6f72c8e3d18f0f204ee8545 (opens in a new tab)
- git.kernel.org/stable/c/1e96239fddcefacf6afe6c498357be68eacbcabc (opens in a new tab)
- git.kernel.org/stable/c/887f92ceccf3eacd5f2402db21254d66372fae00 (opens in a new tab)
- git.kernel.org/stable/c/a5b42c1e4ff2befaa6b96f7cbf32174751eba083 (opens in a new tab)
- git.kernel.org/stable/c/b2eb1ffd511d1b3c3e21122f97cbbccea411e277 (opens in a new tab)
- git.kernel.org/stable/c/b94c4be77682aab06d65ca7296149e3bcfb37353 (opens in a new tab)
- git.kernel.org/stable/c/bd69a825485168ef74e815ecb286754b570fdcc7 (opens in a new tab)
- ubuntu.com/security/CVE-2026-53397 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-53397 (opens in a new tab)
- git.kernel.org/linus/0853ac544c590880d797b04daa33fcb72b6be0e1 (opens in a new tab)
- msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-53397.json (opens in a new tab)
- support.microsoft.com/lifecycle (opens in a new tab)
- first.org/cvss (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8727-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8800-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8886-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-2 (opens in a new tab)