==========================================================Ubuntu Security Notice USN-927-3 April 11, 2010
A security issue affects the following Ubuntu releases:
This advisory also applies to the corresponding versions of
Kubuntu, Edubuntu, and Xubuntu.
The problem can be corrected by upgrading your system to the
following package versions:
After a standard system upgrade you need to restart Thunderbird to effect
the necessary changes.
USN-927-1 fixed vulnerabilities in NSS. Due to upstream changes in NSS
3.12.6, Thunderbird would be unable to initialize the security component
and connect with SSL/TLS if the old libnss3-0d transition package was
installed. This update fixes the problem.
We apologize for the inconvenience.
Original advisory details:
Marsh Ray and Steve Dispensa discovered a flaw in the TLS and SSLv3
protocols. If an attacker could perform a man in the middle attack at the
start of a TLS connection, the attacker could inject arbitrary content at
the beginning of the user's session. This update adds support for the new
new renegotiation extension and will use it when the server supports it.