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CVE-2026-4408

📛 CVE Title

Alpine Linux: CVE-2026-4408: OS Command Injection

⬇ Download JSON ⚠ View as Threat

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.

Description (MITRE) cveawg.mitre.org

Pulled from cveawg.mitre.org/api/cve/CVE-2026-4408 on 2026-08-02. Shown when MITRE's text differs from the cvelistV5 mirror.

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.

Overview

State
—
Assigner (CNA)
—
CVSS severity
MEDIUM
CVSS score
CVSS 5.0 / 10 5.0 5.0 / 10
CVSS vector
AV:N/AC:M/Au:N/C:C/I:C/A:C
Effective score
5.0 / 10 MEDIUM source: CNA overview
CWE(s)
—
Reserved
—
Published
2026-05-28 00:00 UTC
Last updated
—
Source
https://www.rapid7.com/db/vulnerabilities/alpine-linux-cve-2026-4408/
Linked Threat
CVE-2026-4408 — CVE-2026-4408

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published
2026-05-28 09:16:47 UTC
NVD last modified
2026-07-15 02:22:40 UTC
NVD CVSS v3.1
CVSS 9.0 / 10 9.0 9.0 / 10 CRITICAL source: secalert@redhat.com
NVD CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploitability subscore
2.2 / 10
Impact subscore
6.0 / 10
EPSS score
0.0250 (probability of exploitation in next 30 days)
EPSS percentile
83.11% vs all CVEs — higher = more likely to be exploited, as of 2026-08-01

NVD-assigned CWE(s): CWE-78 (differs from the CNA list above)

NVD / KEV / EPSS data refreshed 2026-08-01 17:00 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID
EUVD-2026-32741
Assigner
redhat
Published
May 28, 2026, 7:25:27 AM
Updated
Jul 15, 2026, 12:54:52 AM
EUVD base score (CVSS 3.1)
9.0 / 10
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
EUVD-reported EPSS
2.5000
Vendors
Red Hat
Products
Red Hat Enterprise Linux 10.0 Extended Update Support (patch: 0:4.21.3-114.el10_0.1)
Red Hat Enterprise Linux 9.6 Extended Update Support (patch: 0:4.21.3-14.el9_6.1)
Red Hat Enterprise Linux 8 (patch: 0:4.19.4-16.el8_10)
Red Hat Enterprise Linux 10 (patch: 0:4.23.5-109.el10_2)
Red Hat OpenShift Container Platform 4.20 (patch: 4.20.9.6.202606241928-0)
Red Hat Enterprise Linux 7 Extended Lifecycle Support (patch: 0:4.10.16-26.el7_9.1)
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (patch: 0:4.15.5-16.el8_6.1)
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (patch: 0:4.19.4-105.el9_4.4)
Red Hat Enterprise Linux 9 (patch: 0:4.23.5-10.el9_8)
Red Hat OpenShift Container Platform 4.21 (patch: 4.21.9.6.202606241859-0)
Red Hat OpenShift Container Platform 4.19 (patch: 4.19.9.6.202606241344-0)
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (patch: 0:4.13.3-12.el8_4.1)
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (patch: 0:4.15.5-16.el8_6.1)
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (patch: 0:4.17.5-7.el8_8.1)
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (patch: 0:4.13.3-12.el8_4.1)
Red Hat Enterprise Linux 8.8 Telecommunications Update Service (patch: 0:4.17.5-7.el8_8.1)
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (patch: 0:4.17.5-105.el9_2.5)
Aliases
GHSA-jg8v-92xc-cx65

ENISA 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.

EUVD references (17)

Affected products — CPE 2.3 (5) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

  • cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
  • cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
  • cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
  • cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

Vendor references (0)

References embedded in the original CVE record by the assigning CNA.

None in the CVE record.

MITRE references (12) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

Web references (12)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

NVD-tagged references (34)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

Remediations (13)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

  • Rapid7 — Solution
    rapid7

    ubuntu-upgrade-samba

    2026-06-04 09:02 UTC
  • Rapid7 — Solution
    rapid7

    debian-upgrade-samba

    2026-06-04 08:54 UTC
  • Rapid7 — Solution
    rapid7

    alpine-linux-upgrade-samba

    2026-06-04 08:53 UTC
  • CVE-2026-4408 - Vulnerability Details - OpenCVE
    web:app.opencve.io

    Update to the latest Samba version that removes the vulnerability or apply the vendor's patch as soon as it becomes available. Reconfigure the Samba "check password script" to eliminate the use of the %u substitution, or disable the feature entirely. Apply the official Red Hat workaround provided for this issue as a temporary mitigation .

    2026-06-19 02:28 UTC
  • Security Advisories and Bulletins | Microsoft Learn
    web:learn.microsoft.com

    Learning path Learn how Microsoft supports secure software development as part of a cybersecurity solution - Training Secure software development means integrating security into each phase of your development lifecycle, from requirements analysis to maintenance. Microsoft provides many services that can help you develop more secure code and deploy a more secure application in the cloud. This ...

    2026-06-19 02:28 UTC
  • Nvd - Cve-2026-4408
    web:nvd.nist.gov

    Official websites use .gov A .gov website belongs to an official government organization in the United States.

    2026-06-19 02:28 UTC
  • Security Update Guide - Loading - Microsoft
    web:portal.msrc.microsoft.com

    The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

    2026-06-19 02:28 UTC
  • CVE-2026-4408 - security-tracker.debian.org
    web:security-tracker.debian.org

    Vulnerable and fixed packages The table below lists information on source packages.

    2026-06-19 02:28 UTC
  • CVE-2026-4408 : Remote Command Execution Vulnerability in Samba File ...
    web:securityvulnerability.io

    Discover the remote command execution vulnerability impacting Samba file servers and domain controllers. Learn more about CVE-2026-4408 .

    2026-06-19 02:28 UTC
  • CVE-2026-4408 | Ubuntu
    web:ubuntu.com

    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 ...

    2026-06-19 02:28 UTC
  • CVE-2026-4408 - vulnerability database | Vulners.com
    web:vulners.com

    CVE-2026-4408 : Samba remotely executes code due to a misconfiguration in the "check password script" feature when the script uses the %u substitution. The client-supplied username is passed with insufficient escaping of shell meta-characters, ena...

    2026-06-19 02:28 UTC
  • National Vulnerability Database | NIST
    web:www.nist.gov

    NIST maintains the National Vulnerability Database (NVD), a repository of information on software and hardware flaws that can compromise computer security. This is a key piece of the nation's cybersecurity infrastructure.

    2026-06-19 02:28 UTC
  • CVE-2026-4408 | Tenable®
    web:www.tenable.com

    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 ...

    2026-06-19 02:28 UTC

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-4408.json.

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