firefox is vulnerable to man-in-the-middle (MitM). The vulnerability exists as the Add-On updates did not respect the same certificate trust rules as software updates.
lists.opensuse.org/opensuse-security-announce/2020-07/msg00023.html
lists.opensuse.org/opensuse-security-announce/2020-07/msg00026.html
lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.html
lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.html
access.redhat.com/errata/RHSA-2020:2826
access.redhat.com/security/updates/classification/#important
bugzilla.mozilla.org/show_bug.cgi?id=1308251
security.gentoo.org/glsa/202007-09
security.gentoo.org/glsa/202007-10
usn.ubuntu.com/4421-1/
www.mozilla.org/security/advisories/mfsa2020-24/
www.mozilla.org/security/advisories/mfsa2020-25/
www.mozilla.org/security/advisories/mfsa2020-26/