The remote host is missing an update to libgd announced via advisory USN-33-1.
CVE-2004-0990 described several buffer overflows which had been discovered in libgd's PNG handling functions. Another update is required because the update from USN-21-1 was not sufficient to prevent every possible attack.
If an attacker tricks a user into loading a malicious PNG or XPM image, they could leverage this into executing arbitrary code in the context of the user opening image.
This vulnerability might lead to privilege escalation in customized systems that use server applications which link libgd. However, Warty does not ship such server applications (PHP in Warty uses libgd2 which was already fixed in USN-25-1).
The following packages are affected:
libgd1-noxpm libgd1-xpm
Solution: The problem can be corrected by upgrading the affected package to version 1.8.4-36ubuntu0.2. In general, a standard system upgrade is sufficient to effect the necessary changes.