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Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS : libxmltok vulnerabilities (USN-8872-1)

medium Nessus Plugin ID 363376

Synopsis

The remote Ubuntu host is missing one or more security updates.

Description

The remote Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8872-1 advisory.

 It was discovered that Expat, contained with the xmltok library did not correctly handle certain integer arithmetic. If a user or automated system were tricked into opening a specially crafted file, an attacker could possibly cause a denial of service. (CVE-2026-56404, CVE-2026-56405)

Tenable has extracted the preceding description block directly from the Ubuntu 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

Update the affected libxmltok1 and / or libxmltok1t64 packages.

See Also

https://ubuntu.com/security/notices/USN-8872-1

Plugin Details

Severity: Medium

ID: 363376

File Name: ubuntu_USN-8872-1.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 10/6/2026

Updated: 10/6/2026

Supported Sensors: Continuous Assessment, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.5

Percentile: 57.71

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-2026-56405

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:libxmltok1, p-cpe:/a:canonical:ubuntu_linux:libxmltok1t64

Required KB Items: Host/cpu, Host/Ubuntu, Host/Ubuntu/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 10/5/2026

Vulnerability Publication Date: 6/21/2026

Reference Information

CVE: CVE-2026-56404, CVE-2026-56405

USN: 8872-1