CVE-2026-4408 CRITICAL

CVE-2026-4408: Samba: remote code execution in samr

Vendor Red Hat
Product Red Hat Enterprise Linux 6
Weakness CWE-78
Published May 28, 2026
Last update June 15, 2026

CVSS base score

9.0/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

May 28, 2026 CVE published
June 15, 2026 Record updated