source: https://www.securityfocus.com/bid/7121/info

GNOME Eye of Gnome (EOG) image viewer is prone to a format string vulnerability. This condition may lead to execution of arbitrary code if malicious format specifiers are supplied to the program via the command line. As some utilities may be configured to invoke EOG as the handler for images through a mailcap entry, this may allow for local privilege escalation or possibly remote exploitation.

$ /usr/bin/eog this_is_an_invalid_file_%n%n