A mechanism to spoof the addressbar through the user interaction on the addressbar and the "onblur" event. The event could be used by script to affect text display to make the loaded site appear to be different from the one actually loaded within the addressbar. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 52.1, and Firefox < 53.
https://www.mozilla.org/security/advisories/mfsa2017-13/
https://www.mozilla.org/security/advisories/mfsa2017-12/
https://www.mozilla.org/security/advisories/mfsa2017-10/
https://bugzilla.mozilla.org/show_bug.cgi?id=1273537
https://access.redhat.com/errata/RHSA-2017:1201
https://access.redhat.com/errata/RHSA-2017:1106