ownCloud Desktop Client before 2.0.1, when compiled with a Qt release after 5.3.x, does not call QNetworkReply::ignoreSslErrors with the list of errors to be ignored, which makes it easier for remote attackers to conduct man-in-the-middle (MITM) attacks by leveraging a server using a self-signed certificate.  NOTE: this vulnerability exists because of a partial CVE-2015-4456 regression.