Description of problem: Internationalized domain names exist for quite some time (IDNA2003), although the protocols describing them have evolved in an incompatible way (IDNA2008). These incompatibilities will prevent applications written for IDNA2003 to access certain problematic domain names defined with IDNA2008, e.g., faß.de is translated to domain xn--fa-hia.de with IDNA2008, while in IDNA2003 it is translated to fass.de domain. That not only causes incompatibility problems, but may be used as an attack vector to redirect users to different web sites. The change is about deprecating libidn, which supports IDNA2003, and switch all applications using libidn, to libidn2 2.0.0, which supports IDNA2008. The switch should be transparent as the libidn2 library is API compatible. See instructions at: https://libidn.gitlab.io/libidn2/manual/libidn2.html#Converting-from-libidn This is part of the IDNA2008 change: https://fedoraproject.org/wiki/Changes/IDNA2008 If upstream is not aware of that change please involve them on the process.
I believe this is fixed since curl-7.51.0-1.fc25. Please reopen if it is not. See http://bugzilla.redhat.com/CVE-2016-8625 for details.