Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
As upstream CNA, the severity of "High" seems excessive even in the general case. The only impact here is a DoS and it can easily be mitigated by (in the Red Hat context) dropping the glibc-gconv-extra package or minimally disabling the two gconv errant plugins; those converters are not in common use anyway.