rxvt: unsafe defaulting to using :0 when DISPLAY is unset

rxvt 2.6.4 opens a terminal window on :0 if the DISPLAY environment variable is not set, which might allow local users to hijack X11 connections. NOTE: it was later reported that rxvt-unicode, mrxvt, aterm, multi-aterm, and wterm are also affected. NOTE: realistic attack scenarios require that the victim enters a command on the wrong machine.

The menuBar feature in aterm 0.42 allows attackers to modify menu options and execute arbitrary commands via a certain character escape sequence that inserts the commands into the menu.

The aterm terminal emulator 0.42 allows attackers to modify the window title via a certain character escape sequence and then insert it back to the command line in the user's terminal, e.g. when the user views a file containing the malicious sequence, which could allow the attacker to execute arbitrary commands.