Unfortunately not. It's easy to process UTF-8 such that you mishandle certain ill-formed sequences that you are unlikely to encounter accidentally. IIS was hit [1], Apache Tomcat was hit [2], PHP was hit twice [3] [4].
UTF-16 has its own warts, but invalid code units and non-shortest forms are exclusive to UTF-8.
UTF-16 has its own warts, but invalid code units and non-shortest forms are exclusive to UTF-8.
[1] http://www.sans.org/security-resources/malwarefaq/wnt-unicod...
[2] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-2938
[3] https://www.cvedetails.com/cve/CVE-2009-5016/
[4] https://www.cvedetails.com/cve/CVE-2010-3870/