Claroline is prone to multiple input-validation vulnerabilities:
1. Multiple cross-site scripting vulnerabilities.
2. A remote URI-redirection vulnerability.
An attacker may leverage these issues to execute arbitrary script code in the browser of an unsuspecting user in the context of the affected site and redirect users to an attacker-controlled site; this may aid in phishing-style attacks.
Versions prior to Claroline 1.8.10 are vulnerable.