Problem Description:
Insufficient validation of environment variables in the
telnet client supplied in FreeBSD can lead to stack-based
buffer overflows. A stack- based overflow is present in the
handling of environment variables when connecting via the
telnet client to remote telnet servers.
This issue only affects the telnet client. Inbound telnet
sessions to telnetd(8) are not affected by this issue.
Impact:
These buffer overflows may be triggered when connecting
to a malicious server, or by an active attacker in the
network path between the client and server. Specially crafted
TELNET command sequences may cause the execution of arbitrary
code with the privileges of the user invoking telnet(1).