Vulnerability · Published May 28, 2026 · Assigned by redhat

CVE-2026-4408Samba: remote code execution in samr

Critical 9.0

In plain English

A critical-severity OS command injection in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.5% (higher than 85% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.0Critical

Exploit odds (30 days)2.5%top 15.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack tooling1Public PoC

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
AlmaLinux:8	ctdb	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:10	ldb-tools	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:9	ldb-tools	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	libldb	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:9	libldb	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	libldb-devel	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:9	libldb-devel	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	libnetapi	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	libnetapi	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	libnetapi	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	libnetapi-devel	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	libnetapi-devel	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	libnetapi-devel	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	libsmbclient	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	libsmbclient	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	libsmbclient	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	libsmbclient-devel	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	libsmbclient-devel	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	libsmbclient-devel	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	libwbclient	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	libwbclient	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	libwbclient	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	libwbclient-devel	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	libwbclient-devel	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	libwbclient-devel	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	python3-ldb	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:9	python3-ldb	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	python3-samba	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	python3-samba	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	python3-samba	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	python3-samba-dc	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	python3-samba-dc	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	python3-samba-dc	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:8	python3-samba-devel	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:10	python3-samba-test	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	python3-samba-test	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	python3-samba-test	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-client	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-client	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-client	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-client-libs	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-client-libs	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-client-libs	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-common	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-common	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-common	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-common-libs	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-common-libs	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-common-libs	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-common-tools	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-common-tools	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-common-tools	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-dc-libs	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-dc-libs	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-dc-libs	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-dcerpc	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-dcerpc	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-dcerpc	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-devel	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-devel	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-devel	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-gpupdate	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:9	samba-gpupdate	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-krb5-printing	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-krb5-printing	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-krb5-printing	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-ldb-ldap-modules	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-ldb-ldap-modules	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-ldb-ldap-modules	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-libs	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-libs	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-libs	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-pidl	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-pidl	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-pidl	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-test	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-test	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-test	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-test-libs	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-test-libs	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-test-libs	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-tools	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-tools	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-tools	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-usershares	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-usershares	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-usershares	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-vfs-iouring	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-vfs-iouring	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-vfs-iouring	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-winbind	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-winbind	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-winbind	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-winbind-clients	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-winbind-clients	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-winbind-clients	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-winbind-krb5-locator	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-winbind-krb5-locator	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-winbind-krb5-locator	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-winbind-modules	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-winbind-modules	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-winbind-modules	4.23.5-10.el9_8	ALSA-2026:25049
AlmaLinux:10	samba-winexe	4.23.5-109.el10_2	ALSA-2026:22963
AlmaLinux:8	samba-winexe	4.19.4-16.el8_10	ALSA-2026:22644
AlmaLinux:9	samba-winexe	4.23.5-10.el9_8	ALSA-2026:25049
Alpine:v3.23	samba	4.22.10-r0	ALPINE-CVE-2026-4408
Alpine:v3.24	samba	4.23.8-r0	ALPINE-CVE-2026-4408
Debian:12	samba	2:4.17.12+dfsg-0+deb12u4	DEBIAN-CVE-2026-4408
Debian:13	samba	2:4.22.8+dfsg-0+deb13u2	DEBIAN-CVE-2026-4408
Debian:14	samba	2:4.24.3+dfsg-1	DEBIAN-CVE-2026-4408
Rocky Linux:10	samba	0:4.23.5-109.el10_2	RLSA-2026:22963
Rocky Linux:8	samba	0:4.19.4-16.el8_10	RLSA-2026:22644
Rocky Linux:9	samba	0:4.23.5-10.el9_8	RLSA-2026:25049
Ubuntu:22.04:LTS	samba	2:4.15.13+dfsg-0ubuntu1.12	UBUNTU-CVE-2026-4408
Ubuntu:24.04:LTS	samba	2:4.19.5+dfsg-4ubuntu9.6	UBUNTU-CVE-2026-4408
Ubuntu:25.10	samba	2:4.22.3+dfsg-4ubuntu2.4	UBUNTU-CVE-2026-4408
Ubuntu:26.04:LTS	samba	2:4.23.6+dfsg-1ubuntu2.1	UBUNTU-CVE-2026-4408

Affected products (as reported)

Vendor	Product	Versions
Red Hat	Red Hat Enterprise Linux 10	see references
Red Hat	Red Hat Enterprise Linux 10.0 Extended Update Support	see references
Red Hat	Red Hat Enterprise Linux 7 Extended Lifecycle Support	see references
Red Hat	Red Hat Enterprise Linux 7 Extended Lifecycle Support	see references
Red Hat	Red Hat Enterprise Linux 8	see references
Red Hat	Red Hat Enterprise Linux 8	see references
Red Hat	Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support	see references
Red Hat	Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On	see references
Red Hat	Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support	see references
Red Hat	Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On	see references
Red Hat	Red Hat Enterprise Linux 8.8 Telecommunications Update Service	see references
Red Hat	Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions	see references
Red Hat	Red Hat Enterprise Linux 9	see references
Red Hat	Red Hat Enterprise Linux 9	see references
Red Hat	Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions	see references
Red Hat	Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions	see references
Red Hat	Red Hat Enterprise Linux 9.6 Extended Update Support	see references
Red Hat	Red Hat OpenShift Container Platform 4.12	see references
Red Hat	Red Hat OpenShift Container Platform 4.13	see references
Red Hat	Red Hat OpenShift Container Platform 4.14	see references
Red Hat	Red Hat OpenShift Container Platform 4.15	see references
Red Hat	Red Hat OpenShift Container Platform 4.16	see references
Red Hat	Red Hat OpenShift Container Platform 4.17	see references
Red Hat	Red Hat OpenShift Container Platform 4.18	see references
Red Hat	Red Hat OpenShift Container Platform 4.19	see references
Red Hat	Red Hat OpenShift Container Platform 4.20	see references
Red Hat	Red Hat OpenShift Container Platform 4.21	see references
Red Hat	Red Hat Enterprise Linux 6	see references
Red Hat	Red Hat Enterprise Linux 6	see references

Weakness: CWE-78 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

References

RHSA-2026:22644 vendor-advisory, x_refsource_REDHAT
RHSA-2026:22963 vendor-advisory, x_refsource_REDHAT
RHSA-2026:25049 vendor-advisory, x_refsource_REDHAT
RHSA-2026:25979 vendor-advisory, x_refsource_REDHAT
RHSA-2026:28053 vendor-advisory, x_refsource_REDHAT
RHSA-2026:28054 vendor-advisory, x_refsource_REDHAT
RHSA-2026:28055 vendor-advisory, x_refsource_REDHAT
RHSA-2026:28056 vendor-advisory, x_refsource_REDHAT
RHSA-2026:28057 vendor-advisory, x_refsource_REDHAT
RHSA-2026:28058 vendor-advisory, x_refsource_REDHAT
RHSA-2026:28132 vendor-advisory, x_refsource_REDHAT
RHSA-2026:29799 vendor-advisory, x_refsource_REDHAT
RHSA-2026:29833 vendor-advisory, x_refsource_REDHAT
RHSA-2026:29863 vendor-advisory, x_refsource_REDHAT
RHSA-2026:56786 vendor-advisory, x_refsource_REDHAT
RHSA-2026:56853 vendor-advisory, x_refsource_REDHAT
RHSA-2026:56911 vendor-advisory, x_refsource_REDHAT
RHSA-2026:57483 vendor-advisory, x_refsource_REDHAT
RHSA-2026:59831 vendor-advisory, x_refsource_REDHAT
RHSA-2026:60019 vendor-advisory, x_refsource_REDHAT
RHSA-2026:65839 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2026-4408 vdb-entry, x_refsource_REDHAT
RHBZ#2479762 issue-tracking, x_refsource_REDHAT
https://bugzilla.samba.org/show_bug.cgi?id=16034
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4408.json x_sadp-csaf-vex