Tuleap vulnerable to XSS in the HTML mail content of the cross reference field

Tuleap is a tool for end to end traceability of application and system developments. Prior to Tuleap Community Edition 15.13.99.37, Tuleap Enterprise Edition 15.13-3, and Tuleap Enterprise Edition 15.12-6, a site administrator could create an artifact link type with a forward label allowing them to execute uncontrolled code (or at least achieve content injection) in a mail client. Tuleap Community Edition 15.13.99.37, Tuleap Enterprise Edition 15.13-3, and Tuleap Enterprise Edition 15.12-6 fix this issue.