The ucnv_UTF8FromUTF8 function in ucnv_u8.cpp in International Components
for Unicode (ICU) for C/C++ through 60.1 mishandles ucnv_convertEx calls for
UTF-8 to UTF-8 conversion, which allows remote attackers to cause a denial
of service (stack-based buffer overflow and application crash) or possibly
have unspecified other impact via a crafted string, as demonstrated by ZNC.
Fixed by the noted versions which are already stable in the tree.