Home/CVE/A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain con
CVE
CVE-2026-4408
A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain con
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.
CRITICAL · CVSS 9
EPSS 0.01022
Schedule remediation
- CVSS base score ≥ 7.0
Sigma rules0
YARA rules0
Look this up elsewhere - one-click external pivots
▸
How to read a CVE - triage first, then detect and patch
This page is every public fact about CVE-2026-4408, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.
Triage: should I act now? Four signals, and they are not interchangeable:
CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked.
EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal.
CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score.
Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.
How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.
Then what - two workflows:
Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits.
PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.
Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).
◆
ATT&CK techniques
2Techniques this CVE enables - linked via CWECAPECATT&CK. High◆ = named directly in ATT&CK or Nuclei templates.
▤ Build a SIEM detection for these techniques▤
CAPEC attack patterns
5Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.
⬡
Weakness Classification
📦
Fixed versions by distribution
80The package version that resolves this CVE on each Linux distribution, from the vendor’s published security data. fixed in shows a patched version exists; open means the package is listed as affected with no fix yet.
alpine edgesamba fixed in 4.23.8-r0
oracle allctdb open
oracle alllibnetapi open
oracle alllibnetapi-devel open
oracle alllibsmbclient fixed in 0:4.19.4-16.0.1.el8_10
oracle alllibsmbclient-devel fixed in 0:4.19.4-16.0.1.el8_10
oracle alllibwbclient open
oracle alllibwbclient-devel open
oracle allpython3-samba fixed in 0:4.19.4-16.0.1.el8_10
oracle allpython3-samba-dc open
oracle allpython3-samba-devel fixed in 0:4.19.4-16.0.1.el8_10
oracle allpython3-samba-test open
oracle allsamba open
oracle allsamba-client open
oracle allsamba-client-libs open
oracle allsamba-common open
oracle allsamba-common-libs fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-common-tools fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-dc-libs open
oracle allsamba-dcerpc open
oracle allsamba-devel open
oracle allsamba-krb5-printing fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-ldb-ldap-modules fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-libs fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-pidl open
oracle allsamba-test fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-test-libs fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-tools open
oracle allsamba-usershares fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-vfs-glusterfs fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-vfs-iouring fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-winbind open
oracle allsamba-winbind-clients open
oracle allsamba-winbind-krb5-locator open
oracle allsamba-winbind-modules fixed in 0:4.19.4-16.0.1.el8_10
oracle allsamba-winexe fixed in 0:4.19.4-16.0.1.el8_10
rhel 8ctdb fixed in 0:4.19.4-16.el8_10
rhel 8libnetapi fixed in 0:4.19.4-16.el8_10
rhel 8libnetapi-devel open
rhel 8libsmbclient open
rhel 8libsmbclient-devel open
rhel 8libwbclient open
rhel 8libwbclient-devel fixed in 0:4.19.4-16.el8_10
rhel 8python3-samba open
rhel 8python3-samba-dc open
rhel 8python3-samba-devel open
rhel 8python3-samba-test fixed in 0:4.19.4-16.el8_10
rhel 8samba open
rhel 8samba-client open
rhel 8samba-client-libs open
rhel 8samba-common fixed in 0:4.19.4-16.el8_10
rhel 8samba-common-libs fixed in 0:4.19.4-16.el8_10
rhel 8samba-common-tools fixed in 0:4.19.4-16.el8_10
rhel 8samba-dc-libs open
rhel 8samba-dcerpc fixed in 0:4.19.4-16.el8_10
rhel 8samba-devel fixed in 0:4.19.4-16.el8_10
rhel 8samba-krb5-printing fixed in 0:4.19.4-16.el8_10
rhel 8samba-ldb-ldap-modules open
rhel 8samba-libs fixed in 0:4.19.4-16.el8_10
rhel 8samba-pidl open
rhel 8samba-test fixed in 0:4.19.4-16.el8_10
rhel 8samba-test-libs open
rhel 8samba-tools fixed in 0:4.19.4-16.el8_10
rhel 8samba-usershares open
rhel 8samba-vfs-iouring open
rhel 8samba-winbind open
rhel 8samba-winbind-clients open
rhel 8samba-winbind-krb5-locator fixed in 0:4.19.4-16.el8_10
rhel 8samba-winbind-modules open
rhel 8samba-winexe open
rhel 9ctdb fixed in 0:4.23.5-10.el9_8
rhel 9ldb-tools fixed in 0:4.23.5-10.el9_8
rhel 9libldb fixed in 0:4.23.5-10.el9_8
rhel 9libldb-devel fixed in 0:4.23.5-10.el9_8
rhel 9libnetapi open
rhel 9libnetapi-devel open
rhel 9libsmbclient open
rhel 9libsmbclient-devel open
rhel 9libwbclient fixed in 0:4.23.5-10.el9_8
rhel 9libwbclient-devel fixed in 0:4.23.5-10.el9_8
▣
Scoring & Timeline
9
CRITICAL · CVSS v3.1 · [email protected]
Attack Vector
Network
Adjacent
Local
Physical
Attack Complexity
Low
High
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑
Vendor Advisories
13suse-csafopenSUSE-SU-2026:20905-1
suse-csafSUSE-SU-2026:22045-1
suse-csafSUSE-SU-2026:2108-1
suse-csafopenSUSE-SU-2026:10884-1
🔗
References & Sources
3Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.