Affected: Ubuntu:Pro:14.04:LTS: samba, Ubuntu:Pro:16.04:LTS: samba, Ubuntu:Pro:18.04:LTS: samba, Ubuntu:Pro:20.04:LTS: samba, Ubuntu:22.04:LTS: samba, Ubuntu:24.04:LTS: samba, Ubuntu:26.04:LTS: samba

A flaw was found in samba's pam_winbind. When mkhomedir is enabled, pam_winbind chowns the target account's home directory without validating the path is not a critical system directory such as /. On affected systems, accounts with / as their home directory (a common default for system accounts) can have this triggered not only by root, but by a non-root user holding a narrow sudo delegation to run commands as that account, causing ownership of / to change and resulting in severe denial of service (SSH, sudo, and package-manager failures). The change does not grant write access to / (which ships with restrictive 0555 permissions on RHEL), so the impact is availability loss rather than further privilege escalation.