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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | samba | No fix yet | — |
| Debian 13 | samba | No fix yet | — |
| Debian 12 | samba | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | samba | 2:4.23.6+dfsg-1ubuntu2.2 | — |
| Ubuntu 24.04 LTS | samba | 2:4.19.5+dfsg-4ubuntu9.7 | — |
| Ubuntu 22.04 LTS | samba | 2:4.15.13+dfsg-0ubuntu1.13 | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | samba | No fix yet | — |
| Ubuntu Pro 18.04 LTS | samba | No fix yet | — |
| Ubuntu Pro 16.04 LTS | samba | No fix yet | — |
| Ubuntu Pro 14.04 LTS | samba | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | samba | 4.21.10+git.533.31d7e5508d-150700.3.29.1 | SUSE-SU-2026:3363-1 |
| SLES 15 SP6 | samba | 4.19.8+git.501.67274891bc-150600.3.29.1 | SUSE-SU-2026:3364-1 |
| SLES 15 SP5 | samba | 4.17.12+git.581.f49579c6cd-150500.3.42.1 | SUSE-SU-2026:3365-1 |
| SLES 15 SP4 | samba | 4.15.13+git.808.eeca19f5e1-150400.3.52.1 | SUSE-SU-2026:3362-1 |
| SLES 12 SP5 | samba | 4.15.13+git.729.a8ce057e8d-3.109.1 | SUSE-SU-2026:3367-1 |
Show 12 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | samba | 4.22.11+git.552.66cfeb7de0a-160000.1.1 | SUSE-SU-2026:23152-1, SUSE-SU-2026:23129-1 |
| SLES for SAP 15 SP6 | samba | 4.19.8+git.501.67274891bc-150600.3.29.1 | SUSE-SU-2026:3364-1 |
| SLES for SAP 15 SP5 | samba | 4.17.12+git.581.f49579c6cd-150500.3.42.1 | SUSE-SU-2026:3365-1 |
| SLES for SAP 15 SP4 | samba | 4.15.13+git.808.eeca19f5e1-150400.3.52.1 | SUSE-SU-2026:3362-1 |
| SLES 16.0 | samba | 4.22.11+git.552.66cfeb7de0a-160000.1.1 | SUSE-SU-2026:23152-1, SUSE-SU-2026:23129-1 |
| SLE Micro 6.2 | samba | 4.22.9+git.538.af6cb4fb2e-160000.1.1 | SUSE-SU-2026:23003-1, SUSE-SU-2026:22977-1 |
| SLE Micro 5.5 | samba | 4.17.12+git.581.f49579c6cd-150500.3.42.1 | SUSE-SU-2026:3365-1 |
| SLE Micro 5.4 | samba | 4.15.13+git.808.eeca19f5e1-150400.3.52.1 | SUSE-SU-2026:3362-1 |
| SLE Micro 5.3 | samba | 4.15.13+git.808.eeca19f5e1-150400.3.52.1 | SUSE-SU-2026:3362-1 |
| SLE HPC 15 SP5 | samba | 4.17.12+git.581.f49579c6cd-150500.3.42.1 | SUSE-SU-2026:3365-1 |
| SLE HPC 15 SP4 | samba | 4.15.13+git.808.eeca19f5e1-150400.3.52.1 | SUSE-SU-2026:3362-1 |
| SUSE Enterprise Storage 7.1 | samba | 4.15.13+git.808.eeca19f5e1-150300.3.106.1 | SUSE-SU-2026:3366-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | samba | 4.22.9+git.538.af6cb4fb2e-160000.1.1 | openSUSE-SU-2026:21540-1, openSUSE-SU-2026:21475-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | samba +31 | 2:4.17.12-1.amzn2023.0.7 | ALAS2023-2026-2135 |
| Amazon Linux 2 | ctdb +26 | 4.10.16-24.amzn2.0.9 | ALAS2-2026-3886 |
Advisories 15
- ALAS2023-2026-2135 Important: samba security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 14, 2026
- WID-SEC-2026-2376 Samba: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Aug 31, 2026
- ALAS2-2026-3886 Important: samba security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Aug 31, 2026
- SUSE-SU-2026:23152-1 Security update for samba SUSE / openSUSE Security Updates · Aug 14, 2026
- SUSE-SU-2026:23129-1 Security update for samba SUSE / openSUSE Security Updates · Aug 14, 2026
- SUSE-SU-2026:23003-1 Security update for samba SUSE / openSUSE Security Updates · Aug 12, 2026
- openSUSE-SU-2026:21540-1 Security update for samba SUSE / openSUSE Security Updates · Aug 8, 2026
- SUSE-SU-2026:22977-1 Security update for samba SUSE / openSUSE Security Updates · Aug 4, 2026
- openSUSE-SU-2026:21475-1 Security update for samba SUSE / openSUSE Security Updates · Jul 31, 2026
- SUSE-SU-2026:3364-1 Security update for samba SUSE / openSUSE Security Updates · Jul 29, 2026
- SUSE-SU-2026:3365-1 Security update for samba SUSE / openSUSE Security Updates · Jul 29, 2026
- SUSE-SU-2026:3366-1 Security update for samba SUSE / openSUSE Security Updates · Jul 29, 2026
- SUSE-SU-2026:3367-1 Security update for samba SUSE / openSUSE Security Updates · Jul 29, 2026
- SUSE-SU-2026:3362-1 Security update for samba SUSE / openSUSE Security Updates · Jul 29, 2026
- SUSE-SU-2026:3363-1 Security update for samba SUSE / openSUSE Security Updates · Jul 29, 2026
References
- https://access.redhat.com/security/cve/CVE-2026-15779 vdb-entry
- RHBZ#2499991 issue-tracking
- 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