If right-to-left text is used in the addressbar with left-to-right alignment, it is possible in some circumstances to scroll this text to spoof the displayed URL. This issue could result in the wrong URL being displayed as a location, which can mislead users to believe they are on a different site than the one loaded. This vulnerability affects Thunderbird < 52.6, Firefox ESR < 52.6, and Firefox < 58.
https://www.mozilla.org/security/advisories/mfsa2018-04/
https://www.mozilla.org/security/advisories/mfsa2018-03/
https://www.mozilla.org/security/advisories/mfsa2018-02/
https://www.debian.org/security/2018/dsa-4102
https://www.debian.org/security/2018/dsa-4096
https://usn.ubuntu.com/3544-1/
https://lists.debian.org/debian-lts-announce/2018/01/msg00036.html
https://lists.debian.org/debian-lts-announce/2018/01/msg00030.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1395508
https://access.redhat.com/errata/RHSA-2018:0262
https://access.redhat.com/errata/RHSA-2018:0122