Claroline before 1.8.6 allows remote authenticated administrators to obtain sensitive information via an invalid value in the sort parameter to admin/adminusers.php, which reveals the path in an error message in some circumstances, as demonstrated by a parameter value containing an XSS sequence.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.