By inserting secape sequences into terminal session (via log files, e-mail, etc) it's possible to force client into performing a set of operation, like sending control command to server, create a file, etc.
CVE-2007-0313 (Unspecified vulnerability in GONICUS System Administration (GOsa) before 2.5.8 allows remote authenticated users to modify certain settings, including the admin password, via crafted POST requests.)