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Ubuntu Security Notice USN-1262-1
November 15, 2011

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

- Ubuntu 11.10

Summary:

Several security issues were fixed in Light Display Manager.

Software Description:
- lightdm: Display Manager

Details:

It was discovered that Light Display Manager incorrectly handled privileges
when reading .dmrc files. A local attacker could exploit this issue to read
arbitrary configuration files, bypassing intended permissions.
(CVE-2011-3153)

It was discovered that Light Display Manager incorrectly handled links when
adjusting permissions on .Xauthority files. A local attacker could exploit
this issue to access arbitrary files, and possibly obtain increased
privileges. In the default Ubuntu installation, this would be prevented
by the Yama link restrictions. (CVE-2011-4105)

Update instructions:

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

Ubuntu 11.10:
  liblightdm-gobject-1-0          1.0.6-0ubuntu1.1
  liblightdm-qt-1-0               1.0.6-0ubuntu1.1
  lightdm                         1.0.6-0ubuntu1.1

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

References:
  http://www.ubuntu.com/usn/usn-1262-1
  CVE-2011-3153, CVE-2011-4105

Package Information:
  https://launchpad.net/ubuntu/+source/lightdm/1.0.6-0ubuntu1.1