CVE-2026-4408
Description
A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain controllers that use the "check password script" feature. If this script is configured with the %u substitution character, the client-controlled username is passed without proper escaping of shell meta-characters. This vulnerability allows an attacker to achieve remote command execution on the affected system. This issue primarily affects non-standard configurations where the "check password script" is used with %u and the samba-dcerpcd service is started as a system service.
How to fix
- samba samba4.21.0 or later
- bugzilla.samba.org/show_bug.cgi?id=16034
- access.redhat.com/errata/RHSA-2026:22644
- access.redhat.com/errata/RHSA-2026:22963
- access.redhat.com/errata/RHSA-2026:25049
- access.redhat.com/errata/RHSA-2026:25979
- access.redhat.com/errata/RHSA-2026:28053
- access.redhat.com/errata/RHSA-2026:28054
- access.redhat.com/errata/RHSA-2026:28055
- access.redhat.com/errata/RHSA-2026:28056
- access.redhat.com/errata/RHSA-2026:28057
- access.redhat.com/errata/RHSA-2026:28058
- access.redhat.com/errata/RHSA-2026:28132
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| samba samba | 4.1.0 ≤ v < 4.21.0 | 4.21.0 |
| redhat openshift_container_platform | 4.0 | — |
| redhat enterprise_linux | 6.0, 7.0, 9.0 | — |
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