Mailing the story:
Avoid Common Pitfalls in Greasemonkey: How the History of Greasemonkey Security Affects You Now
Once upon a time, there was a security hole. (This is not your standard fairy tale. Stay with me.) Greasemonkey's architecture has changed substantially since it was first written. Version 0.3, the first version to gain wide popularity, had a fundamental security flaw: it trusted the remote page too much when it injected and executed user scripts.