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Ubuntu Security Notice USN-1232-1
October 18, 2011

xorg-server vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 11.10
- Ubuntu 11.04
- Ubuntu 10.10
- Ubuntu 10.04 LTS

Summary:

The X server could be made to crash, run programs as an administrator, or
read arbitrary files.

Software Description:
- xorg-server: X.Org X server

Details:

It was discovered that the X server incorrectly handled certain malformed
input. An authorized attacker could exploit this to cause the X server to
crash, leading to a denial or service, or possibly execute arbitrary code
with root privileges. This issue only affected Ubuntu 10.04 LTS and 10.10.
(CVE-2010-4818)

It was discovered that the X server incorrectly handled certain malformed
input. An authorized attacker could exploit this to cause the X server to
crash, leading to a denial or service, or possibly read arbitrary data from
the X server process. This issue only affected Ubuntu 10.04 LTS.
(CVE-2010-4819)

Vladz discovered that the X server incorrectly handled lock files. A local
attacker could use this flaw to determine if a file existed or not.
(CVE-2011-4028)

Vladz discovered that the X server incorrectly handled setting lock file
permissions. A local attacker could use this flaw to gain read permissions
on arbitrary files and view sensitive information. (CVE-2011-4029)

Update instructions:

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

Ubuntu 11.10:
  xserver-xorg-core               2:1.10.4-1ubuntu4.1

Ubuntu 11.04:
  xserver-xorg-core               2:1.10.1-1ubuntu1.3

Ubuntu 10.10:
  xserver-xorg-core               2:1.9.0-0ubuntu7.5

Ubuntu 10.04 LTS:
  xserver-xorg-core               2:1.7.6-2ubuntu7.8

After a standard system update you need to restart your session to make
all the necessary changes.

References:
  http://www.ubuntu.com/usn/usn-1232-1
  CVE-2010-4818, CVE-2010-4819, CVE-2011-4028, CVE-2011-4029

Package Information:
  https://launchpad.net/ubuntu/+source/xorg-server/2:1.10.4-1ubuntu4.1
  https://launchpad.net/ubuntu/+source/xorg-server/2:1.10.1-1ubuntu1.3
  https://launchpad.net/ubuntu/+source/xorg-server/2:1.9.0-0ubuntu7.5
  https://launchpad.net/ubuntu/+source/xorg-server/2:1.7.6-2ubuntu7.8