CVE-2026-4408Samba: 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.

Timeline

Scores

EPSS (exploitation in 30 days)

46.9% · top 1.2% of all CVEs (12 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.0.

Affected products

• Red Hat · Red Hat Enterprise Linux 10

  • unaffected 0:4.23.5-109.el10_2 – < *

• Red Hat · Red Hat Enterprise Linux 10.0 Extended Update Support

  • unaffected 0:4.21.3-114.el10_0.1 – < *

• Red Hat · Red Hat Enterprise Linux 7 Extended Lifecycle Support

  • unaffected 0:4.10.16-26.el7_9.1 – < *

• Red Hat · Red Hat Enterprise Linux 7 Extended Lifecycle Support

  • unaffected 0:4.10.16-26.el7_9.1 – < *

• Red Hat · Red Hat Enterprise Linux 8

  • unaffected 0:4.19.4-16.el8_10 – < *

• Red Hat · Red Hat Enterprise Linux 8

  • unaffected 0:4.19.4-16.el8_10 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support

  • unaffected 0:4.13.3-12.el8_4.1 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

  • unaffected 0:4.13.3-12.el8_4.1 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support

  • unaffected 0:4.15.5-16.el8_6.1 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

  • unaffected 0:4.15.5-16.el8_6.1 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Telecommunications Update Service

  • unaffected 0:4.17.5-7.el8_8.1 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions

  • unaffected 0:4.17.5-7.el8_8.1 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:4.23.5-10.el9_8 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:4.23.5-10.el9_8 – < *

• Red Hat · Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

  • unaffected 0:4.17.5-105.el9_2.5 – < *

• Red Hat · Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

  • unaffected 0:4.19.4-105.el9_4.4 – < *

• Red Hat · Red Hat Enterprise Linux 9.6 Extended Update Support

  • unaffected 0:4.21.3-14.el9_6.1 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.12

  • unaffected 412.86.202608241157-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.13

  • unaffected 413.92.202609080414-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.14

  • unaffected 414.92.202608172040-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.15

  • unaffected 415.92.202608180329-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.16

  • unaffected 416.94.202608150307-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.17

  • unaffected 417.94.202608250221-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.18

  • unaffected 418.94.202608142238-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.19

  • unaffected 4.19.9.6.202606241344-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.20

  • unaffected 4.20.9.6.202606241928-0 – < *

• Red Hat · Red Hat OpenShift Container Platform 4.21

  • unaffected 4.21.9.6.202606241859-0 – < *

• Red Hat · Red Hat Enterprise Linux 6

  All versions: unknown

• Red Hat · Red Hat Enterprise Linux 6

  All versions: unknown

What to do

Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-32741 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-4408](https://cveledger.app/badge/CVE-2026-4408.svg)](https://cveledger.app/cve/CVE-2026-4408)

Record last updated 4 Nov 2026, 22:27 UTC.