Due to a missing case handling object types, a type confusion vulnerability could occur, resulting in a crash. We presume that with enough effort that it could be exploited to run arbitrary code. This vulnerability affects Firefox ESR < 68.4 and Firefox < 72.
https://www.mozilla.org/security/advisories/mfsa2020-02/
https://www.mozilla.org/security/advisories/mfsa2020-01/
https://www.debian.org/security/2020/dsa-4603
https://www.debian.org/security/2020/dsa-4600
https://usn.ubuntu.com/4335-1/
https://usn.ubuntu.com/4241-1/
https://usn.ubuntu.com/4234-1/
https://security.gentoo.org/glsa/202003-02
https://seclists.org/bugtraq/2020/Jan/26
https://seclists.org/bugtraq/2020/Jan/18
https://seclists.org/bugtraq/2020/Jan/12
https://lists.debian.org/debian-lts-announce/2020/01/msg00016.html
https://lists.debian.org/debian-lts-announce/2020/01/msg00005.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1603055
https://access.redhat.com/errata/RHSA-2020:0295
https://access.redhat.com/errata/RHSA-2020:0292
https://access.redhat.com/errata/RHSA-2020:0127
https://access.redhat.com/errata/RHSA-2020:0123
https://access.redhat.com/errata/RHSA-2020:0120
https://access.redhat.com/errata/RHSA-2020:0111
https://access.redhat.com/errata/RHSA-2020:0086
https://access.redhat.com/errata/RHSA-2020:0085
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00043.html
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00029.html