The remote host is missing an update to openssl announced via advisory USN-339-1.
A security issue affects the following Ubuntu releases:
Ubuntu 5.04 Ubuntu 5.10 Ubuntu 6.06 LTS
This advisory also applies to the corresponding versions of Kubuntu, Edubuntu, and Xubuntu.
Philip Mackenzie, Marius Schilder, Jason Waddle and Ben Laurie of Google Security discovered that the OpenSSL library did not sufficiently check the padding of PKCS #1 v1.5 signatures if the exponent of the public key is 3 (which is widely used for CAs). This could be exploited to forge signatures without the need of the secret key.
Solution: The problem can be corrected by upgrading your system to the following package versions:
Ubuntu 5.04: libssl0.9.7 0.9.7e-3ubuntu0.3
Ubuntu 5.10: libssl0.9.7 0.9.7g-1ubuntu1.2
Ubuntu 6.06 LTS: libssl0.9.8 0.9.8a-7ubuntu0.1
After a standard system upgrade you need to reboot your computer to effect the necessary changes.