The remote host is missing an update to libsoup announced via advisory USN-737-1.
Details follow:
It was discovered that the Base64 encoding functions in libsoup did not properly handle large strings. If a user were tricked into connecting to a malicious server, an attacker could possibly execute arbitrary code with user privileges.
Solution: The problem can be corrected by upgrading your system to the following package versions:
Ubuntu 6.06 LTS: libsoup2.2-8 2.2.93-0ubuntu1.2
Ubuntu 7.10: libsoup2.2-8 2.2.100-1ubuntu0.1
In general, a standard system upgrade is sufficient to effect the necessary changes.