A STUN server in conjunction with a large number of "webkitRTCPeerConnection" objects can be used to send large STUN packets in a short period of time due to a lack of rate limiting being applied on e10s systems, allowing for a denial of service attack. This vulnerability affects Firefox < 51.
https://www.mozilla.org/security/advisories/mfsa2017-01/
https://bugzilla.mozilla.org/show_bug.cgi?id=1281482