Currently there is a security bug in the openssl library.
It should be carried out an update as soon as possible for services using SSL.
You can check on the page http://filippo.io/Heartbleed/ whether your server is affected
After the update, all services that use SSL/TLS must be restarted. (Apache, postfix, ...)
http://heartbleed.com/
http://www.debian.org/security/2014/dsa-2896