https://blog.torproject.org/blog/tor-02234- released-security-patches Tor before 0.2.2.34, when configured as a bridge, uses direct DirPort access instead of a Tor TLS connection for a directory fetch, which makes it easier for remote attackers to enumerate bridges by observing DirPort connections.
Created tor tracking bugs for this issue Affects: fedora-all [bug 771512] Affects: epel-all [bug 771513]
Current EPEL and Fedora provide 0.2.3.25 which includes this fix.