Cyber Posture

CVE-2026-4408

CriticalRCE
Microsoft: not affectedMSmacOS: not affectedMacLinux: not affectedLnxMobile: not affectedMobNetwork: not affectedNetApplication: not affectedAppOther: affectedOth

Published: 28 May 2026

Published
28 May 2026
Modified
28 May 2026
KEV Added
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Patch
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CVSS Score 9.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.0023 46.4th percentile
Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-4408 is a critical-severity OS Command Injection (CWE-78) vulnerability in Samba (inferred from references). Its CVSS base score is 9.0 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 46.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique.
Threat & Defense Details

Likely Mitigating ControlsAI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-27 Platform-independent Applications
addresses: CWE-78

Platform-independent apps typically execute inside a managed runtime or sandbox that restricts direct OS command execution, reducing the ability to exploit OS command injection.

SI-10 Information Input Validation
addresses: CWE-78

Validates inputs to block special elements that would alter OS command execution.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
attack.mitre.org →
Why these techniques?

Direct OS command injection (CWE-78) in public-facing Samba service enables remote code execution via unsanitized input to shell script.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD 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…

more

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.

Deeper analysisAI

Automated synthesis unavailable for this CVE.

Details

CWE(s)
CWE-78
OWASP Top 10 Web 2025
A05:2025

Affected Products

Samba
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inferred from references and description; NVD did not file a CPE for this CVE

EU & UK References

Regulatory context (EU CRA / NIS2 / DORA / UK NIS Regulations)

EU Cyber Resilience Act — coordinated disclosure

Critical and high-severity vulnerabilities in products with digital elements may trigger coordinated-disclosure obligations under the EU Cyber Resilience Act (CRA, Regulation 2024/2847). Manufacturers placing products on the EU market must notify ENISA and the relevant CSIRTs without undue delay once active exploitation is known.

References