An issue was discovered in SugarCRM before 7.7.2.3, 7.8.x before 7.8.2.2, and 7.9.x before 7.9.2.0 (and Sugar Community Edition 6.5.26). The WebToLeadCapture functionality is found vulnerable to unauthenticated cross-site scripting (XSS) attacks. This attack vector is mitigated by proper validating the redirect URL values being passed along.
https://www.synology.com/support/security/Synology_SA_17_53_SugarCRM
https://support.sugarcrm.com/Resources/Security/sugarcrm-sa-2017-008/