The REST interface in Cisco Spark 2015-06 allows remote authenticated users to obtain sensitive information via a request for an unspecified file, aka Bug ID CSCuv84048.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2016-2422
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160210-sp2