A vulnerability where a WebExtension can run content scripts in disallowed contexts following navigation or other events. This allows for potential privilege escalation by the WebExtension on sites where content scripts should not be run. This vulnerability affects Firefox ESR < 60.3 and Firefox < 63.
https://www.mozilla.org/security/advisories/mfsa2018-27/
https://www.mozilla.org/security/advisories/mfsa2018-26/
https://www.debian.org/security/2018/dsa-4324
https://usn.ubuntu.com/3801-1/
https://security.gentoo.org/glsa/201811-04
https://lists.debian.org/debian-lts-announce/2018/11/msg00008.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1483602
https://access.redhat.com/errata/RHSA-2018:3006
https://access.redhat.com/errata/RHSA-2018:3005