There is an interesting vulnerability in the default behavior of Firefox builtin popup blocker. This vulnerability, coupled with an additional trick, allows the attacker to read arbitrary user-accessible files on the system, and thus steal some fairly sensitive information. This was tested on 1.5.0.9.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/54194/firefox-popup.txt
Source: https://packetstormsecurity.com/files/54194/firefox-popup.txt.html