An attacker could trick Software Center into installing altered packages and repositories or exposing sensitive information over the network.

=========================================================================Ubuntu Security Notice USN-1270-1
November 21, 2011

software-center vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 11.10
- Ubuntu 11.04
- Ubuntu 10.10

Summary:

An attacker could trick Software Center into installing altered packages
and repositories or exposing sensitive information over the network.

Software Description:
- software-center: Utility for browsing, installing, and removing software

Details:

David B. discovered that Software Center incorrectly validated server
certificates when performing secure connections. If a remote attacker were
able to perform a man-in-the-middle attack, this flaw could be exploited to
view sensitive information or install altered packages and repositories.

Update instructions:

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

Ubuntu 11.10:
  software-center                 5.0.2ubuntu0.1

Ubuntu 11.04:
  software-center                 4.0.5ubuntu0.1

Ubuntu 10.10:
  software-center                 3.0.10ubuntu0.1

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-1270-1
  CVE-2011-3150

Package Information:
  https://launchpad.net/ubuntu/+source/software-center/5.0.2ubuntu0.1
  https://launchpad.net/ubuntu/+source/software-center/4.0.5ubuntu0.1
  https://launchpad.net/ubuntu/+source/software-center/3.0.10ubuntu0.1