USN-1197-6: Qt vulnerability

22 September 2011

qt4-x11 vulnerability

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

  • Ubuntu 11.04
  • Ubuntu 10.10
  • Ubuntu 10.04 LTS


A certificate authority mis-issued fraudulent certificates.

Software Description

  • qt4-x11 - Qt 4 libraries and support modules


USN-1197-1 and USN-1197-3 addressed an issue in Firefox and Xulrunner pertaining to the Dutch Certificate Authority DigiNotar mis-issuing fraudulent certificates. This update provides an update for Qt that blacklists the known fraudulent certificates.

Original advisory details: USN-1197-1

It was discovered that Dutch Certificate Authority DigiNotar had mis-issued multiple fraudulent certificates. These certificates could allow an attacker to perform a “man in the middle” (MITM) attack which would make the user believe their connection is secure, but is actually being monitored.

For the protection of its users, Mozilla has removed the DigiNotar certificate. Sites using certificates issued by DigiNotar will need to seek another certificate vendor.

We are currently aware of a regression that blocks one of two Staat der Nederlanden root certificates which are believed to still be secure. This regression is being tracked at


USN-1197-1 partially addressed an issue with Dutch Certificate Authority DigiNotar mis-issuing fraudulent certificates. This update actively distrusts the DigiNotar root certificate as well as several intermediary certificates. Also included in this list of distrusted certificates are the “PKIOverheid” (PKIGovernment) intermediates under DigiNotar’s control that did not chain to DigiNotar’s root and were not previously blocked.

Update instructions

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

Ubuntu 11.04
libqt4-network - 4:4.7.2-0ubuntu6.3
Ubuntu 10.10
libqt4-network - 4:4.7.0-0ubuntu4.4
Ubuntu 10.04 LTS
libqt4-network - 4:4.6.2-0ubuntu5.3

To update your system, please follow these instructions:

After a standard system upgrade you need to restart your session to effect the necessary changes.