USN-1990-1: X.Org X server vulnerabilities

17 October 2013

xorg-server, xorg-server-lts-quantal, xorg-server-lts-raring vulnerabilities

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 13.04
  • Ubuntu 12.10
  • Ubuntu 12.04 LTS


The X.Org X server could be made to crash or run programs as an administrator if it received specially crafted input.

Software Description

  • xorg-server - X.Org X11 server
  • xorg-server-lts-quantal - X.Org X11 server
  • xorg-server-lts-raring - X.Org X11 server


Pedro Ribeiro discovered that the X.Org X server incorrectly handled memory operations when handling ImageText requests. An attacker could use this issue to cause X.Org to crash, or to possibly execute arbitrary code. (CVE-2013-4396)

It was discovered that non-root X.Org X servers such as Xephyr incorrectly used cached xkb files. A local attacker could use this flaw to cause a xkb cache file to be loaded by another user, resulting in a denial of service. (CVE-2013-1056)

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 13.04
xserver-xorg-core - 2:1.13.3-0ubuntu6.2
Ubuntu 12.10
xserver-xorg-core - 2:1.13.0-0ubuntu6.4
Ubuntu 12.04 LTS
xserver-xorg-core - 2:1.11.4-0ubuntu10.14
xserver-xorg-core-lts-quantal - 2:1.13.0-0ubuntu6.1~precise4
xserver-xorg-core-lts-raring - 2:1.13.3-0ubuntu6~precise3

To update your system, please follow these instructions:

After a standard system update you need to reboot your computer to make all the necessary changes.