Bugzilla before 3.2.10, 3.4.x before 3.4.10, 3.6.x before 3.6.4, and 4.0.x before 4.0rc2 creates a clickable link for a (1) javascript: or (2) data: URI in the URL (aka bug_file_loc) field, which allows remote attackers to conduct cross-site scripting (XSS) attacks against logged-out users via a crafted URI.