firefox is vulnerable to cross-site scripting (XSS). Failure to correctly handle null bytes when processing HTML entities results in incorrectly parsing of these entities, leading to HTML comment text being treated as HTML which could result in an XSS in a web application under certain conditions.
access.redhat.com/errata/RHSA-2019:3193
access.redhat.com/security/updates/classification/#critical
bugzilla.mozilla.org/show_bug.cgi?id=1584216
security.gentoo.org/glsa/202003-10
usn.ubuntu.com/4335-1/
www.mozilla.org/security/advisories/mfsa2019-33/
www.mozilla.org/security/advisories/mfsa2019-34/
www.mozilla.org/security/advisories/mfsa2019-35/