Drupal security advisory – If someone creates a clever enough URL and convinces you to click on it, and you later log in but you do not log off then the attacker may be able to impersonate you.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/44645/DRUPAL-SA-2006-003.txt
Source: https://packetstormsecurity.com/files/44645/DRUPAL-SA-2006-003.txt.html