Tuleap does not sanitize properly user inputs when constructing a SQL query for removing a cross reference.
Impact
An attacker could execute arbitrary SQL queries.
CVSSv2 score: 6 (AV:N/AC:M/Au:S/C:P/I:P/A:P)
Exploitation
The page <tuleap_url>/reference/rmreference.php is exploitable via the parameter target_type, the attacker must be a project administrator for at least one project.
The vulnerability can be demonstrated using this query:
<tuleap_url>/reference/rmreference.php?target_gid=<project_id>&source_gid=<project_id>&target_type=' and 1=(select benchmark(5000000,md5('a'))) or '
When the vulnerability is present, the query will take a large amount of time to be executed by the DBMS.
References
https://cwe.mitre.org/data/definitions/89.html
https://www.owasp.org/index.php/SQL_Injection