A serious issue was discovered this week in the OpenSSL packages distributed with Debian based distributions over the last year and a half. The issue revolves around a small piece of code that was removed, it turned out that removing this bit of code crippled the pseudo random number generator used when creating keys. The vulnerable code has been using only the process id of the service as the seed, which leaves a very small number of seeds that can be used (32,768 to be exact).
All SSL and SSH keys generated affected systems since September 2006 could be affected. All generated certificates will be need to recreated and resigned by the CA. This includes web site certificates as well as OpenVPN certificates. If your CA was created on an affected system, it will also need to be recreated, and the old one revoked. As for SSH, any systems using key authentication need to be audited. If the keys were generated on these affected systems, they should be updated and regenerated ASAP.
Debian and Ubuntu have released updated packages, as well as a tool for checking your keys. Upon installing the packages, it is possible to recreate the keys during the update. These updates should be installed immediately, and keys regenerated after installing the updates.