source: http://www.securityfocus.com/bid/18078/info

Dia is prone to a remote format-string vulnerability. 

This issue arises when the application handles specially crafted filenames. An attacker can exploit this vulnerability by crafting a malicious filename that contains format specifiers and then coercing unsuspecting users to open the malicious file with the affected application.

A successful attack may crash the application or lead to arbitrary code execution. 

This issue affects Dia versions 0.95 and earlier.

The following filename is sufficient to demonstrate this issue:
%p%p%p%p.bmp