If you get the error
socket: (13) Permission denied
while trying to connect to the cache manager of Squid using cachemgr.cgi, it probably means SElinux is enabled and is preventing cgi files from making TCP connections.
Quick and dirty fix : disabling SElinux
Change the value SELINUX to “disabled”
Clean fix : make a rule in SElinux to allow the connection
I don’t know much about SElinux yet, so if someone feels like pointing me to the right direction or submitting something, it is welcomed :)