The remote host is missing an update to the system as announced in the referenced advisory FreeBSD-SA-05:01.telnet.asc

Upgrade your system to the appropriate stable release or security branch dated after the correction date https://secure1.securityspace.com/smysecure/catid.html?in=FreeBSD-SA-05:01.telnet.asc

The telnet(1) command is a TELNET protocol client, used primarily to establish terminal sessions across a network. Buffer overflows were discovered in the env_opt_add() and slc_add_reply() functions of the telnet(1) command. TELNET protocol commands, options, and data are copied from the network to a fixed-sized buffer. In the case of env_opt_add (CVE-2005-0468), the buffer is located on the heap. In the case of slc_add_reply (CVE-2005-0469), the buffer is global uninitialized data (BSS).