Public vulnerability disclosure

CVE-2026-4408

Samba: remote code execution in samr

publishedCWE-78

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.

Technical severity9.0 criticalCVSS 3.1 · CNA: redhat
Published2026-05-28Source updated 2026-11-03
Collected2026-11-032 attributed sources

Fixes and workarounds

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.

Source: CNA: redhat

Fix

RHSA-2026:28132: Red Hat Enterprise Linux Server (v. 7 ELS), Red Hat Enterprise Linux Server Optional (v. 7 ELS), Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS) RHSA-2026:59831: Red Hat OpenShift Container Platform 4.12 RHSA-2026:65839: Red Hat OpenShift Container Platform 4.13 RHSA-2026:56786: Red Hat OpenShift Container Platform 4.14 RHSA-2026:56911: Red Hat OpenShift Container Platform 4.15 RHSA-2026:56853: Red Hat OpenShift Container Platform 4.16 RHSA-2026:60019: Red Hat OpenShift Container Platform 4.17 RHSA-2026:57483: Red Hat OpenShift Container Platform 4.18 RHSA-2026:29863: Red Hat OpenShift Container Platform 4.19 RHSA-2026:29799: Red Hat OpenShift Container Platform 4.20 RHSA-2026:29833: Red Hat OpenShift Container Platform 4.21 RHSA-2026:28055: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux BaseOS EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) RHSA-2026:22963: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) RHSA-2026:22644: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8) RHSA-2026:28057: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6), Red Hat Enterprise Linux BaseOS AUS (v.8.6), Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) RHSA-2026:28056: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8), Red Hat Enterprise Linux BaseOS E4S (v.8.8), Red Hat Enterprise Linux BaseOS TUS (v.8.8) RHSA-2026:28054: Red Hat Enterprise Linux AppStream E4S (v.9.2), Red Hat Enterprise Linux BaseOS E4S (v.9.2), Red Hat Enterprise Linux Resilient Storage E4S (v.9.2) RHSA-2026:28053: Red Hat Enterprise Linux AppStream E4S (v.9.4), Red Hat Enterprise Linux BaseOS E4S (v.9.4), Red Hat Enterprise Linux Resilient Storage E4S (v.9.4) RHSA-2026:25979: Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat Enterprise Linux BaseOS EUS (v.9.6), Red Hat Enterprise Linux Resilient Storage EUS (v.9.6) RHSA-2026:25049: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Resilient Storage (v. 9) RHSA-2026:28058: Red Hat Enterprise Linux BaseOS AUS (v.8.4), Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4)

Source: ADP: redhat-SADP

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.

Source: ADP: redhat-SADP

Affected products and versions

Affected products, source version ranges and reporting authorities
ProductVersionsAuthority
Red Hat Enterprise Linux 10
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.23.5-109.el10_2; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 10.0 Extended Update Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.21.3-114.el10_0.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 7 Extended Lifecycle Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.10.16-26.el7_9.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 8
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.19.4-16.el8_10; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.13.3-12.el8_4.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.13.3-12.el8_4.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.15.5-16.el8_6.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.15.5-16.el8_6.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.17.5-7.el8_8.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.17.5-7.el8_8.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 9
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.23.5-10.el9_8; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.17.5-105.el9_2.5; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.19.4-105.el9_4.4; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 9.6 Extended Update Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.21.3-14.el9_6.1; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.12
Red Hat
openshift/ose-rhel-coreos-8
https://access.redhat.com/downloads/content/package-browser/
≥ 412.86.202608241157-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.13
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 413.92.202609080414-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.14
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 414.92.202608172040-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.15
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 415.92.202608180329-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.16
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 416.94.202608150307-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.17
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 417.94.202608250221-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.18
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 418.94.202608142238-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.19
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 4.19.9.6.202606241344-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.20
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 4.20.9.6.202606241928-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat OpenShift Container Platform 4.21
Red Hat
openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/
≥ 4.21.9.6.202606241859-0; < * (unaffected, rpm)
Other versions: affected
CNA: redhat
Red Hat Enterprise Linux 6
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
Range not reported
Other versions: unknown
CNA: redhat
Red Hat Enterprise Linux 6
Red Hat
samba4
https://access.redhat.com/downloads/content/package-browser/
Range not reported
Other versions: unknown
CNA: redhat
Red Hat Enterprise Linux 10
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.23.5-109.el10_2; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 10.0 Extended Update Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.21.3-114.el10_0.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 7 Extended Lifecycle Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.10.16-26.el7_9.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 8
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.19.4-16.el8_10; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.13.3-12.el8_4.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.13.3-12.el8_4.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.15.5-16.el8_6.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.15.5-16.el8_6.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.17.5-7.el8_8.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.17.5-7.el8_8.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 9
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.23.5-10.el9_8; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.17.5-105.el9_2.5; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.19.4-105.el9_4.4; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 9.6 Extended Update Support
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
≥ 0:4.21.3-14.el9_6.1; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.12
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 412.86.202608241157-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.13
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 413.92.202609080414-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.14
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 414.92.202608172040-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.15
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 415.92.202608180329-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.16
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 416.94.202608150307-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.17
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 417.94.202608250221-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.18
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 418.94.202608142238-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.19
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 4.19.9.6.202606241344-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.20
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 4.20.9.6.202606241928-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4.21
Red Hat
rhcos
https://access.redhat.com/downloads/content/package-browser/
≥ 4.21.9.6.202606241859-0; < * (unaffected, rpm)
Other versions: affected
ADP: redhat-SADP
Red Hat Enterprise Linux 6
Red Hat
samba
https://access.redhat.com/downloads/content/package-browser/
Range not reported
Other versions: unknown
ADP: redhat-SADP
Red Hat Enterprise Linux 6
Red Hat
samba4
https://access.redhat.com/downloads/content/package-browser/
Range not reported
Other versions: unknown
ADP: redhat-SADP
Red Hat OpenShift Container Platform 4
Red Hat
openshift/ose-rhel-coreos-8
https://access.redhat.com/downloads/content/package-browser/
Range not reported
Other versions: affected
ADP: redhat-SADP

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

CVSS assessments

CVSS scores, vectors and reporting authorities
Version / scoreVectorAuthority
3.1 / 9.0
critical
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:HCNA: redhat
3.1 / 9.0
critical
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:HADP: redhat-SADP

Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

References

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