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Fencer Vulns
medium 6.1

CVE-2026-15779 json

Samba-winbind: samba: pam_winbind mkhomedir chowns critical system paths without validation

published 2026-07-15 3 mo ago modified 2026-11-05 3 d ago also EUVD-2026-44662

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

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.

Patch / fix

  • samba Ubuntu 22.04 LTS 2:4.15.13+dfsg-0ubuntu1.13
  • samba Ubuntu 24.04 LTS 2:4.19.5+dfsg-4ubuntu9.7
  • samba Ubuntu 26.04 LTS 2:4.23.6+dfsg-1ubuntu2.2

ubuntu advisories UBUNTU-CVE-2026-15779

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • samba SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 4.22.11+git.552.66cfeb7de0a-160000.1.1
  • samba Linux Micro 6.2 4.22.9+git.538.af6cb4fb2e-160000.1.1
  • samba SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS, SLE High Availability Extension 12 SP5 4.15.13+git.729.a8ce057e8d-3.109.1
  • samba Enterprise Storage 7.1 4.15.13+git.808.eeca19f5e1-150300.3.106.1
  • samba SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +3 more 4.17.12+git.581.f49579c6cd-150500.3.42.1
  • samba SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE High Availability Extension 15 SP6 4.19.8+git.501.67274891bc-150600.3.29.1
  • samba SLE Module for Basesystem 15 SP7, SLE High Availability Extension 15 SP7 4.21.10+git.533.31d7e5508d-150700.3.29.1
  • samba SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +4 more 4.15.13+git.808.eeca19f5e1-150400.3.52.1

suse advisories SUSE-SU-2026:23003-1SUSE-SU-2026:23129-1SUSE-SU-2026:23152-1SUSE-SU-2026:22977-1SUSE-SU-2026:3367-1SUSE-SU-2026:3366-1

  • samba openSUSE Leap 16.0 4.22.11+git.552.66cfeb7de0a-160000.1.1
  • samba openSUSE Leap 16.0 4.22.9+git.538.af6cb4fb2e-160000.1.1

opensuse advisories openSUSE-SU-2026:21540-1openSUSE-SU-2026:21475-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-15779 updated cvss 6.1

samba-winbind: samba: pam_winbind mkhomedir chowns critical system paths without validation

  • Red Hat Enterprise Linux 6 samba-winbind Red Hat Enterprise Linux 7 samba-winbind
    affected: workaround, no fix planned “Do not enable mkhomedir in pam_winbind.conf on systems where any account (including system accounts) may resolve to a home directory of / or another sensitive system path.”
  • Red Hat Enterprise Linux 8 samba-winbind Red Hat Enterprise Linux 9 samba-winbind Red Hat Enterprise Linux 10 samba-winbind 4.23.5-109.el10_2
    affected: workaround, no fix available “Do not enable mkhomedir in pam_winbind.conf on systems where any account (including system accounts) may resolve to a home directory of / or another sensitive system path.”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.10% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

Affected products

  • 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

Classification

Weakness
  • CWE-732 Incorrect Permission Assignment for Critical Resource

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.