More information about this security flaw is available in the following bug: https://bugzilla.redhat.com/show_bug.cgi?id=2373726 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.
clamav-unofficial-sigs is only an signature downloader. Doesn't scan files, so it cann't be affected.