Debian DSA-4920-1 : libx11 - security update

critical Nessus Plugin ID 149897


The remote Debian host is missing a security-related update.


Roman Fiedler reported that missing length validation in various functions provided by libx11, the X11 client-side library, allow to inject X11 protocol commands on X clients, leading to authentication bypass, denial of service or potentially the execution of arbitrary code.


Upgrade the libx11 packages.

For the stable distribution (buster), this problem has been fixed in version 2:1.6.7-1+deb10u2.

See Also

Plugin Details

Severity: Critical

ID: 149897

File Name: debian_DSA-4920.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, cpe:/o:debian:debian_linux:10.0

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

DSA: 4920