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VulnerabilityPublished Updated

CVE-2026-31710: Linux kernel · smb: client: fix dir separator in SMB1 UNIX mounts

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 5.5 Medium · fixed in 7.0.0-28.28~24.04.1 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 22:37 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 7.0.0-28.28~24.04.1, 7.0.0-27.27, 7.0.0-1008.8 +6
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 5 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-27.27
Fixed in
  • 7.0.0-27.27
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1008.8
Fixed in
  • 7.0.0-1008.8
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1010.10
Fixed in
  • 7.0.0-1010.10
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1009.9
Fixed in
  • 7.0.0-1009.9
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1007.7
Fixed in
  • 7.0.0-1007.7
Ubuntu 26.04 LTSlinux-ibmpkg:deb/ubuntu/linux-ibm?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1009.9
Fixed in
  • 7.0.0-1009.9

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 by upgrading to Linux kernel versions 7.0.0-27.27 or later as listed in the fixed versions. The vendor advisory from Ubuntu confirms the availability of this fix. No additional mitigation actions are required beyond applying the official update.

Description

A vulnerability in the Linux kernel SMB client related to SMB1 UNIX mounts has been fixed. The issue involved incorrect handling of directory separators due to missing CIFS mount flags, which could cause improper path handling. This flaw was addressed by ensuring correct updates to mount flags after resetting UNIX capabilities. The vulnerability affects multiple Linux kernel versions prior to 7.0.0-27.27 and related builds. A patch is available in Linux kernel versions 7.0.0-27.27 and later.

References

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