wu-ftpd S/KEY authentication overflow

The remote Wu-FTPd server seems to be vulnerable to a remote overflow.

This version contains a remote overflow if s/key support is enabled. The skey_challenge function fails to perform bounds checking on the name variable resulting in a buffer overflow. With a specially crafted request, an attacker can execute arbitrary code resulting in a loss of integrity and/or availability. It appears that this vulnerability may be exploited prior to authentication. It is reported that S/Key support is not enabled by default, though some operating system distributions which ship Wu-Ftpd may have it enabled.

Upgrade to Wu-FTPd 2.6.3 when available or disable SKEY or apply the patches available at the referenced vendor homepage.