Improper Initialization in Linux kernel - CVE-2026-31710

Vulnerability identifier: #VU128977

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-31710

CWE-ID: CWE-665

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause incorrect path handling.

The vulnerability exists due to improper state management in cifs_mount_get_tcon() for SMB1 UNIX mounts when updating mount flags during mount processing. A local user can trigger the use of incorrect directory separators in paths to cause incorrect path handling.

The issue occurs when SMB1 UNIX mounts are used and the CIFS_MOUNT_POSIX_PATHS bit is missing from mnt_cifs_flags.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-ibm (Ubuntu package)
linux-azure-fde (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-27.27
linux-realtime (Ubuntu package) - update to 7.0.0-27.27.1
linux-gcp (Ubuntu package) - update to 7.0.0-1007.7
linux-oracle (Ubuntu package) - update to 7.0.0-1007.7
linux-aws (Ubuntu package) - update to 7.0.0-1008.8
linux-raspi (Ubuntu package) - update to 7.0.0-1014.14
linux-azure (Ubuntu package) - update to 7.0.0-1010.10
linux-nvidia (Ubuntu package) - update to 7.0.0-1013.13
linux-ibm (Ubuntu package) - update to 7.0.0-1009.9
linux-azure-fde (Ubuntu package) - update to 7.0.0-1009.9

• https://git.kernel.org/stable/c/c4d3fc5844d685441befd0caaab648321013cdfd
• https://git.kernel.org/stable/c/fbbfcf35e1ee3396631f3dc6214cb626aa9814c3

• Improper Initialization in Linux kernel smb client
• Ubuntu update for linux
• Ubuntu update for linux-raspi
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-azure