The remote host is missing an update to the system as announced in the referenced advisory.
The following packages are affected: wu-ftpd wu-ftpd+ipv6
CVE-2005-0256 The wu_fnmatch function in wu_fnmatch.c for wu-fptd 2.6.1 and 2.6.2 allows remote attackers to cause a denial of service (CPU exhaustion by recursion) via a glob pattern with a large number of * (wildcard) characters, as demonstrated using the dir copmmand.
Solution: Update your system with the appropriate patches or software upgrades.