USN-1197-2: Thunderbird vulnerability

USN-1197-1 fixed a vulnerability in Firefox with regard to the DigiNotar
certificate authority. This update provides the corresponding updates for
Thunderbird.

We are aware that the DigiNotar Root CA Certificate is still shown as
trusted in the Thunderbird certificate manager. This is due to Thunderbird
using the system version of the Network Security Service libraries (NSS).
Thunderbird will actively distrust any certificate signed by this DigiNotar
Root CA certificate. This means that users will still get an untrusted
certificate warning when accessing a service through Thunderbird that
presents a certificate signed by this DigiNotar Root CA certificate.

Original advisory details:

It was discovered that Dutch Certificate Authority DigiNotar had
mis-issued multiple fraudulent certificates. These certificates could allow
an attacker to perform a “machine-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 https://launchpad.net/bugs/838322.