Detections
Analytics

Amazon Linux 2 : samba, --advisory ALAS2-2026-3493 (ALAS-2026-3493)

critical Nessus Plugin ID 325585

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of samba installed on the remote host is prior to 4.10.16-24. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3493 advisory.

 unauthenticated udp packet crashes AD DC nbt server (CVE-2026-3238)

 Samba file servers and classic (non-AD) domain controllers offer theSamValidatePasswordChange and SamValidatePasswordReset RPC services on theSAMR DCE/RPC service when running over NCACN_IP_TCP. Both services pass ausername and password to the check password script that can be configuredin smb.conf.

 If the check password script is configured with the %usubstitution character, the client-controlled username is passed tothe check password script without escaping shell meta-characters,leading to a remote command execution vulnerability.

 This is a non-standard configuration in several ways:

 It affects Samba file servers and classic (non-AD) domain controllersthat have the check password script configured with the %usubstitution character. Active Directory Domain Controllers are notaffected, they do not expand the username via the %u substitutioncharacter.

 The problem is much less dangerous if %u has single quotes directlyaround it, e.g. '%u', but it's still possible to injectcommand line options.

 Standard Samba file servers and classic domain controllers are alsoonly affected if the samba-dcerpcd service is started as a systemservice, which can only happen if rpc start on demand helpers is setto the non-default setting no. In the default configuration forDCE/RPC, smbd starts the samba-dcerpcd in a way that makes thevulnerable code inaccessible. (CVE-2026-4408)

 Samba passes the client-controlled job description string to thecommand configured with the print command setting via the %Jsubstitution character without escaping shell meta characters. Thisleads to a remote code execution vulnerability.

 Print servers configured with printing = cups or printing =iprint, and print servers that do not have the %J substitutioncharacter in the print command setting are not affected.

 The problem is much less dangerous if %J has single quotes directlyaround it, e.g. '%J', but it's still possible to injectcommand line options.

 By default, print servers allow guest users to print. (CVE-2026-4480)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update samba' or or 'yum update --advisory ALAS2-2026-3493' to update your system.

See Also

https://alas.aws.amazon.com//AL2/ALAS2-2026-3493.html

https://alas.aws.amazon.com/faqs.html

https://explore.alas.aws.amazon.com/CVE-2026-3238.html

https://explore.alas.aws.amazon.com/CVE-2026-4408.html

https://explore.alas.aws.amazon.com/CVE-2026-4480.html

Plugin Details

Severity: Critical

ID: 325585

File Name: al2_ALAS-2026-3493.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 7/8/2026

Updated: 7/8/2026

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.7

Percentile: 99.06

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-4480

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:libsmbclient, p-cpe:/a:amazon:linux:samba, p-cpe:/a:amazon:linux:samba-pidl, p-cpe:/a:amazon:linux:libwbclient, p-cpe:/a:amazon:linux:samba-common-libs, p-cpe:/a:amazon:linux:samba-libs, p-cpe:/a:amazon:linux:samba-winbind-krb5-locator, p-cpe:/a:amazon:linux:samba-python, p-cpe:/a:amazon:linux:ctdb-tests, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:samba-test, p-cpe:/a:amazon:linux:samba-client-libs, p-cpe:/a:amazon:linux:ctdb, p-cpe:/a:amazon:linux:samba-dc, p-cpe:/a:amazon:linux:samba-test-libs, p-cpe:/a:amazon:linux:samba-vfs-glusterfs, p-cpe:/a:amazon:linux:libwbclient-devel, p-cpe:/a:amazon:linux:samba-winbind-clients, p-cpe:/a:amazon:linux:samba-krb5-printing, p-cpe:/a:amazon:linux:samba-winbind, p-cpe:/a:amazon:linux:samba-debuginfo, p-cpe:/a:amazon:linux:samba-python-test, p-cpe:/a:amazon:linux:samba-client, p-cpe:/a:amazon:linux:samba-common-tools, p-cpe:/a:amazon:linux:samba-devel, p-cpe:/a:amazon:linux:samba-common, p-cpe:/a:amazon:linux:libsmbclient-devel, p-cpe:/a:amazon:linux:samba-dc-libs, p-cpe:/a:amazon:linux:samba-winbind-modules

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 7/8/2026

Vulnerability Publication Date: 5/26/2026

Reference Information

CVE: CVE-2026-3238, CVE-2026-4408, CVE-2026-4480

IAVA: 2026-A-0510