TestLink 1.9.20 is vulnerable to Incorrect Access Control in the TestPlan editing section. When a new TestPlan is created, an ID with an incremental value is automatically generated. Using the edit function you can change the tplan_id parameter to another ID. The application does not carry out a check on the user's permissions maing it possible to recover the IDs of all the TestPlans (even the administrative ones) and modify them even with minimal privileges.
TestLink before v.1.9.20 is vulnerable to Cross Site Scripting (XSS) via the pop-up on upload file. When uploading a file, the XSS payload can be entered into the file name.
In TestLink 1.9.20, the lib/cfields/cfieldsExport.php goback_url parameter causes a security risk because it depends on client input and is not constrained to lib/cfields/cfieldsView.php at the web site associated with the session.
A SQL injection vulnerability in TestLink 1.9.20 allows attackers to execute arbitrary SQL commands in dragdroptreenodes.php via the node_id parameter.