Detections
Analytics
Amazon Linux 2 : expat, --advisory ALAS2-2026-3800 (ALAS-2026-3800)
medium Nessus Plugin ID 328824
Synopsis
The remote Amazon Linux 2 host is missing a security update.Description
The version of expat installed on the remote host is prior to 2.1.0-15. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3800 advisory.libexpat before 2.8.2 has an integer overflow in storeAtts. (CVE-2026-56403)
libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was present in XML_Parse. (CVE-2026-56406)
libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity textLen. (CVE-2026-56407)
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 expat' or or 'yum update --advisory ALAS2-2026-3800' to update your system.See Also
https://alas.aws.amazon.com//AL2/ALAS2-2026-3800.html
https://alas.aws.amazon.com/faqs.html
https://explore.alas.aws.amazon.com/CVE-2026-56403.html
Plugin Details
Severity: Medium
ID: 328824
File Name: al2_ALAS-2026-3800.nasl
Version: 1.1
Type: Local
Agent: unix
Published: 7/21/2026
Updated: 7/21/2026
Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.5
Percentile: 57.58
CVSS v2
Risk Factor: Medium
Base Score: 5.9
Temporal Score: 4.4
Vector: CVSS2#AV:L/AC:H/Au:N/C:C/I:C/A:P
CVSS Score Source: CVE-2026-56407
CVSS v3
Risk Factor: Medium
Base Score: 6.9
Temporal Score: 6
Vector: CVSS:3.0/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
CVSS Score Source: CVE-2026-56403
Vulnerability Information
CPE: cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:expat-debuginfo, p-cpe:/a:amazon:linux:expat-devel, p-cpe:/a:amazon:linux:expat-static, p-cpe:/a:amazon:linux:expat
Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list
Exploit Ease: No known exploits are available
Patch Publication Date: 7/20/2026
Vulnerability Publication Date: 6/21/2026
Reference Information
CVE: CVE-2026-56403, CVE-2026-56406, CVE-2026-56407
IAVA: 2026-A-0650