CVE-2026-4408Network attack vector

Unauthenticated command injection via unescaped SAMR username

Published May 28, 2026 · Updated Aug 31, 2026

OS command injection in Samba SAMR DCE/RPC allows remote attackers to execute commands through a client-controlled username. The SamValidatePasswordChange and SamValidatePasswordReset services pass an unescaped username into a configured check password script, allowing shell metacharacters to alter the command. Exploitation requires a file server or classic domain controller with %u in that script and samba-dcerpcd running as a system service; Active Directory domain controllers and default on-demand startup are not exposed.

CVSS severity9.0
Critical
EPSS probability2.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Samba SAMR DCE/RPC allows remote attackers to execute commands through a client-controlled username. The SamValidatePasswordChange and SamValidatePasswordReset services pass an unescaped username into a configured check password script, allowing shell metacharacters to alter the command. Exploitation requires a file server or classic domain controller with %u in that script and samba-dcerpcd running as a system service; Active Directory domain controllers and default on-demand startup are not exposed.

The record

CVE
CVE-2026-4408
Published
May 28, 2026
Updated
Aug 31, 2026
Vendor
389 Directory Server
Product
Red Hat OpenShift Container Platform 4.16
Classifications
CWE-78, T1059.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 31, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

389 Directory Server · Red Hat OpenShift Container Platform 4.16Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.21Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.8 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.18Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.4 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.15Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.2 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.19Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.14Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-OnAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.8 Telecommunications Update ServiceAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 7 Extended Lifecycle SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10.0 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.6 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.20Affected versions are unavailable in this record.

Published CVSS scores

10.0Samba TeamCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
9.0Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059.004Unix Shell

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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