Samba: remote code execution in samr
Summary
| CVE | CVE-2026-4408 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-28 09:16:47 UTC |
| Updated | 2026-07-03 13:17:25 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 9.8 CRITICAL from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.025010000 probability, percentile 0.827780000 (date 2026-07-05)
Problem Types: CWE-78 | CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | ADP | CVSS | 9 | CRITICAL | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
| 3.1 | [email protected] | Secondary | 9 | CRITICAL | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 9 | CRITICAL | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 9 | CRITICAL | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Operating System | Redhat | Enterprise Linux | 6.0 | All | All | All |
| Operating System | Redhat | Enterprise Linux | 7.0 | All | All | All |
| Operating System | Redhat | Enterprise Linux | 9.0 | All | All | All |
| Application | Redhat | Openshift Container Platform | 4.0 | All | All | All |
| Application | Samba | Samba | All | All | All | All |
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| access.redhat.com/security/cve/CVE-2026-4408 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | Third Party Advisory |
| access.redhat.com/errata/RHSA-2026:22644 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | Issue Tracking |
| access.redhat.com/errata/RHSA-2026:28055 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:29833 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:28132 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:28058 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:28057 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4408.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:28053 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:28056 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:29863 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:25049 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:22963 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | Issue Tracking |
| access.redhat.com/errata/RHSA-2026:25979 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:29799 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| bugzilla.samba.org/show_bug.cgi | [email protected] | bugzilla.samba.org | Issue Tracking, Vendor Advisory |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | Issue Tracking, Third Party Advisory |
| access.redhat.com/errata/RHSA-2026:28054 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank John Walker (ZeroPath) and Ron Ben Yizhak (SafeBreach) for reporting this issue. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-05-19T09:24:56.961Z | Reported to Red Hat. |
| CNA | 2026-05-26T00:00:00.000Z | Made public. |
| ADP | 2026-05-19T09:24:56.961Z | Reported to Red Hat. |
| ADP | 2026-05-26T00:00:00.000Z | Made public. |
Solutions
ADP: 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)
ADP: RHSA-2026:29863: Red Hat OpenShift Container Platform 4.19
ADP: RHSA-2026:29799: Red Hat OpenShift Container Platform 4.20
ADP: RHSA-2026:29833: Red Hat OpenShift Container Platform 4.21
ADP: 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)
ADP: 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)
ADP: RHSA-2026:22644: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8)
ADP: 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)
ADP: 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)
ADP: 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)
ADP: 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)
ADP: 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)
ADP: 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)
ADP: RHSA-2026:28058: Red Hat Enterprise Linux BaseOS AUS (v.8.4), Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4)
Workarounds
CNA: 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.
ADP: 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.