CVE-2026-4408
Samba: remote code execution in samr
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.
INFO
Published Date :
May 28, 2026, 9:16 a.m.
Last Modified :
May 28, 2026, 9:16 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-4408
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 53f830b8-0a3f-465b-8143-3b8a9948e749 | ||||
| CVSS 3.1 | CRITICAL | [email protected] |
Solution
- Remove the '%u' substitution from 'check password script'.
- Update the Samba software to the latest version.
- Ensure samba-dcerpcd is not running as a system service.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-4408.
| URL | Resource |
|---|---|
| https://access.redhat.com/security/cve/CVE-2026-4408 | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2479762 | |
| https://bugzilla.samba.org/show_bug.cgi?id=16034 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-4408 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-4408
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-4408 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-4408 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
May. 28, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H Added CWE CWE-78 Added Reference https://access.redhat.com/security/cve/CVE-2026-4408 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2479762 Added Reference https://bugzilla.samba.org/show_bug.cgi?id=16034