CVE-2026-15779

Description

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.

CVSS Vector

References

• https://access.redhat.com/security/cve/CVE-2026-15779
• https://bugzilla.redhat.com/show_bug.cgi?id=2499991
• https://gitlab.com/samba-team/samba/-/blob/samba-4.19.4/nsswitch/pam_winbind.c
• https://gitlab.com/samba-team/samba/-/blob/samba-4.23.5/nsswitch/pam_winbind.c#L1622
• https://gitlab.com/samba-team/samba/-/blob/samba-4.24.3/nsswitch/pam_winbind.c#L1590