Race condition in the setsid function in Linux before 2.6.8.1 allows local users to cause a denial of service (crash) and possibly access portions of kernel memory, related to TTY changes, locking, and semaphores.
Format string vulnerability in the SSL_set_verify function in telnetd.c for SSLtelnet daemon (SSLtelnetd) 0.13 allows remote attackers to execute arbitrary code.
Buffer overflow in BSD-based telnetd telnet daemon on various operating systems allows remote attackers to execute arbitrary commands via a set of options including AYT (Are You There), which is not properly handled by the telrcv function.