Medium [CVE-2026-15779] pam_winbind mkhomedir chowns critical system paths without validation
This medium-severity Red Hat Linux advisory covers CVE-2026-15779 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
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. Red Hat Product Security rates this flaw's impact as Moderate.
Exploitation requires mkhomedir to be explicitly enabled in pam_winbind.conf, a non-default option used specifically in Active Directory domain-integration deployments, and a PAM session to be opened for an account whose home directory resolves to /.
While the most direct trigger is root running su to such an account, a non-root user holding a narrow sudo delegation to run a command as that account can reach the same code path.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; and 2 more.
Is CVE-2026-15779 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-15779 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-15779?
The advisory VulniPulse tracks names no fixed release. Follow Red Hat's guidance for workarounds and updates.
Confirm against the vendor advisory before you patch.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 5 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 5 days ago·verify at source
Mitigation checklist
- 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.
Official advisory · high-confidence parse· fetched 5 days ago·verify at source
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