GNU XEmacs

gnuserv before 3.12, as shipped with XEmacs, does not properly check the specified length of an X Windows MIT-MAGIC-COOKIE cookie, which allows remote attackers to execute arbitrary commands via a buffer overflow, or brute force authentication by using a short cookie length.

Format string vulnerability in the movemail utility in (1) Emacs 20.x, 21.3, and possibly other versions, and (2) XEmacs 21.4 and earlier, allows remote malicious POP3 servers to execute arbitrary code via crafted packets.

Emacs 21 and XEmacs automatically load and execute .flc (fast lock) files that are associated with other files that are edited within Emacs, which allows user-assisted attackers to execute arbitrary code.