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

Ubuntu Security Notice USN-1990-1

17th 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.

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.

Update instructions

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

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-lts-quantal 2:1.13.0-0ubuntu6.1~precise4
xserver-xorg-core 2:1.11.4-0ubuntu10.14
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.


CVE-2013-1056, CVE-2013-4396