source: http://www.securityfocus.com/bid/5137/info

Blackboard is reportedly prone to cross-site scripting attacks. This issue was reported to be in the login.pl script. The vulnerable script fails to sanitize HTML tags from CGI parameters.

Attackers may exploit this condition via a malicious link to a site running the vulnerable software. Successful exploitation will enable an attacker to cause script code to be executed in the web browser of a user who visits the malicious link.

It has been reported that there other instances where Blackboard fails to sanitize arbitrary HTML and script code. 

http://target/bin/login.pl?course_id=">&lt;SCRIPT&gt;alert()&lt;/SCRIPT&gt;