CVE-2026-4408

Advisory lineage Upstream: 0 Downstream: 20
Modified
Published: 28 May 2026, 07:25
Last modified:15 Jul 2026, 00:54

Vulnerability Summary

Overall Risk (default)
high
70/100
CVSS Score
9.8 CRITICAL
v3.1 (nvd)
EPSS Score
2.5% LOW
3% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

28 May 2026, 07:25
Published
Vulnerability first disclosed
15 Jul 2026, 00:54
Last Modified
Vulnerability information updated

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 Metrics

  • v3.1•CRITICAL•Score: 9CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
  • v3.1•CRITICAL•Score: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 2.50%• Percentile: 83%

Techniques & Countermeasures

  • CWE-78•Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

    The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Affected Systems

  • redhat•enterprise_linux

    6.0 | 7.0 | 9.0

  • redhat•openshift_container_platform

    4.0

  • Unknown•Samba

    ≥ 4.1.0, < 4.21.0

References (18)