CVE 2009-3007

Mozilla Firefox 3.5.1 and SeaMonkey 1.1.17, and Flock 2.5.1, allow context-dependent attackers to spoof the address bar, via window.open with a relative URI, to show an arbitrary file: URL after a victim has visited any file: URL, as demonstrated by a visit to a file: document written by the attacker.

See the CVE page on Mitre.org for more details.