CVE-2026-4408
A remote attacker can exploit a misconfiguration in Samba file servers and classic domain controllers that use the "check password script" feature.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 2.50% probability · 84th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-78
- Affected
- redhat/openshift container platform · samba/samba · redhat/enterprise linux
- Source
- secalert@redhat.com
References
- https://access.redhat.com/errata/RHSA-2026:22644Issue Tracking
- https://access.redhat.com/errata/RHSA-2026:22963Issue Tracking
- https://access.redhat.com/errata/RHSA-2026:25049
- https://access.redhat.com/errata/RHSA-2026:25979
- https://access.redhat.com/errata/RHSA-2026:28053
- https://access.redhat.com/errata/RHSA-2026:28054
- https://access.redhat.com/errata/RHSA-2026:28055
- https://access.redhat.com/errata/RHSA-2026:28056
- https://access.redhat.com/errata/RHSA-2026:28057
- https://access.redhat.com/errata/RHSA-2026:28058
- https://access.redhat.com/errata/RHSA-2026:28132
- https://access.redhat.com/errata/RHSA-2026:29799
- https://access.redhat.com/errata/RHSA-2026:29833
- https://access.redhat.com/errata/RHSA-2026:29863
- https://access.redhat.com/errata/RHSA-2026:56786
- https://access.redhat.com/errata/RHSA-2026:56853
- https://access.redhat.com/errata/RHSA-2026:56911
- https://access.redhat.com/errata/RHSA-2026:57483
- https://access.redhat.com/errata/RHSA-2026:59831
- https://access.redhat.com/errata/RHSA-2026:60019
- https://access.redhat.com/security/cve/CVE-2026-4408Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2479762Issue Tracking, Third Party Advisory
- https://bugzilla.samba.org/show_bug.cgi?id=16034Issue Tracking, Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:22644Issue Tracking
- https://access.redhat.com/errata/RHSA-2026:22963Issue Tracking
- https://access.redhat.com/errata/RHSA-2026:25049
- https://access.redhat.com/errata/RHSA-2026:25979
- https://access.redhat.com/errata/RHSA-2026:28053
- https://access.redhat.com/errata/RHSA-2026:28054
- https://access.redhat.com/errata/RHSA-2026:28055
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.