[ASA-202105-12] libx11: insufficient validation

[Jonas Witschel]

Arch Linux Security Advisory ASA-202105-12
==========================================

Severity: High
Date    : 2021-05-19
CVE-ID  : CVE-2021-31535
Package : libx11
Type    : insufficient validation
Remote  : No
Link    : https://security.archlinux.org/AVG-1968

Summary
=======

The package libx11 before version 1.7.1-1 is vulnerable to insufficient
validation.

Resolution
==========

Upgrade to 1.7.1-1.

# pacman -Syu "libx11>=1.7.1-1"

The problem has been fixed upstream in version 1.7.1.

Workaround
==========

None.

Description
===========

A security issue has been found in libx11 before version 1.7.1.
XLookupColor() and other X libraries function lack proper validation of
the length of their string parameters. If those parameters can be
controlled by an external application (for instance a color name that
can be emitted via a terminal control sequence) it can lead to the
emission of extra X protocol requests to the X server.

Impact
======

An attacker could emit arbitrary X protocol requests to the X server
through crafted string parameters.

References
==========

https://unparalleled.eu/publications/2021/advisory-unpar-2021-1.txt
https://unparalleled.eu/blog/2021/20210518-using-xterm-to-navigate-the-huge-color-space/
https://gitlab.freedesktop.org/xorg/lib/libx11/-/commit/8d2e02ae650f00c4a53deb625211a0527126c605
https://security.archlinux.org/CVE-2021-31535
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