Provide references for CVE-2018-16221.
Where can I find more information about CVE-2018-16221?
References are available at: https://www.sit.fraunhofer.de/de/securitytestlab/, https://www.sit.fraunhofer.de/fileadmin/dokumente/CVE/Advisory_Yealink_Ultra-elegantIPPhone_SIPT41P.pdf?_=1549375271.