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Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS / 26.10 : libXtst vulnerabilities (USN-8939-1)

critical Nessus Plugin ID 367752

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Synopsis

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

Description

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS / 26.10 host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-8939-1 advisory.

 It was discovered that libXtst did not properly handle certain RECORD replies from the X server. A malicious X server could possibly use this issue to cause libXtst clients to crash, resulting in a denial of service. (CVE-2026-94286)

 Tobias Stoeckmann discovered that libXtst did not properly handle certain memory operations. A malicious X server could possibly use this issue to cause libXtst to access memory out of bounds, resulting in a denial of service. This issue only affected Ubuntu 16.04 LTS. (CVE-2016-7951)

 Tobias Stoeckmann discovered that libXtst did not properly handle certain replies from the X server. A malicious X server could possibly use this issue to cause libXtst to enter an infinite loop, resulting in a denial of service. This issue only affected Ubuntu 16.04 LTS. (CVE-2016-7952)

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 libxtst6 package.

See Also

https://ubuntu.com/security/notices/USN-8939-1

Plugin Details

Severity: Critical

ID: 367752

File Name: ubuntu_USN-8939-1.nasl

Version: 1.3

Type: Local

Agent: unix

Published: 10/20/2026

Updated: 10/21/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, 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: 4.9

Percentile: 58.5

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 5.5

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

CVSS Score Source: CVE-2016-7951

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

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:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, 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, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.10, p-cpe:/a:canonical:ubuntu_linux:libxtst6

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

Exploit Ease: No known exploits are available

Patch Publication Date: 10/19/2026

Vulnerability Publication Date: 10/19/2026

Reference Information

CVE: CVE-2016-7951, CVE-2016-7952, CVE-2026-94286

USN: 8939-1