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 “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 <https://launchpad.net/bugs/838322>.