Debian DLA-2666-1 : libx11 security update

critical Nessus Plugin ID 149889


The remote Debian host is missing a security update.


Roman Fiedler found that libX11, the X11 protocol client library, was vulnerable to protocol command injection due to insufficient validation of arguments to some functions.

For Debian 9 stretch, this problem has been fixed in version 2:1.6.4-3+deb9u4.

We recommend that you upgrade your libx11 packages.

For the detailed security status of libx11 please refer to its security tracker page at:

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.


Upgrade the affected packages.

See Also

Plugin Details

Severity: Critical

ID: 149889

File Name: debian_DLA-2666.nasl

Version: 1.3

Type: local

Agent: unix

Published: 5/25/2021

Updated: 6/14/2021

Supported Sensors: Agentless Assessment, Frictionless Assessment Agent, Nessus Agent

Risk Information


Risk Factor: Medium

Score: 6.7


Risk Factor: High

Base Score: 7.5

Temporal Score: 5.9

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

Temporal Vector: E:POC/RL:OF/RC:C

CVSS Score Source: CVE-2021-31535


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: E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:debian:debian_linux:libx11-6, p-cpe:/a:debian:debian_linux:libx11-6-udeb, p-cpe:/a:debian:debian_linux:libx11-data, p-cpe:/a:debian:debian_linux:libx11-dev, p-cpe:/a:debian:debian_linux:libx11-doc, p-cpe:/a:debian:debian_linux:libx11-xcb-dev, p-cpe:/a:debian:debian_linux:libx11-xcb1, cpe:/o:debian:debian_linux:9.0

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 5/24/2021

Vulnerability Publication Date: 5/27/2021

Reference Information

CVE: CVE-2021-31535