SB2026092578 - Incorrect permission assignment for critical resource in Linux kernel smb server

Description

This security bulletin contains information about 1 vulnerability.

1) Incorrect permission assignment for critical resource (CVE-ID: CVE-2026-93786)

CWE-ID: CWE-732 - Incorrect Permission Assignment for Critical Resource

CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a remote user to widen effective permissions on SMB-created objects.

The vulnerability exists due to improper permission assignment in the ksmbd VFS POSIX ACL inheritance handling when creating SMB objects in directories with default POSIX ACLs. A remote user can create an SMB object to widen effective permissions on that object.

Exploitation requires a parent directory with a default POSIX ACL containing a restrictive ACL_MASK entry.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/0093909becbda22b62b39b654dbc607faed59cd0
• https://git.kernel.org/stable/c/591acf171644de590cda245fd8595b473a1beb70
• https://git.kernel.org/stable/c/e148e567a9252643baa125cb65d7ae9c2c6cf68a