The Math.random function in the JavaScript implementation in Mozilla Firefox 3.5.x before 3.5.10 and 3.6.x before 3.6.4, and SeaMonkey before 2.0.5, uses a random number generator that is seeded only once per browser session, which makes it easier for remote attackers to track a user, or trick a user into acting upon a spoofed pop-up message, by calculating the seed value, related to a "temporary footprint" and an "in-session phishing attack."