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.
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00029.html
https://access.redhat.com/errata/RHSA-2020:0085
https://access.redhat.com/errata/RHSA-2020:0086
https://access.redhat.com/errata/RHSA-2020:0111
https://access.redhat.com/errata/RHSA-2020:0120
https://access.redhat.com/errata/RHSA-2020:0123
https://access.redhat.com/errata/RHSA-2020:0127
https://bugzilla.mozilla.org/show_bug.cgi?id=1603055
https://lists.debian.org/debian-lts-announce/2020/01/msg00005.html
https://lists.debian.org/debian-lts-announce/2020/01/msg00016.html
https://seclists.org/bugtraq/2020/Jan/12
https://seclists.org/bugtraq/2020/Jan/18
https://seclists.org/bugtraq/2020/Jan/26
https://usn.ubuntu.com/4234-1/
https://usn.ubuntu.com/4241-1/
https://www.debian.org/security/2020/dsa-4600
https://www.debian.org/security/2020/dsa-4603
Source: MITRE
Published: 2020-01-08
Updated: 2020-01-13
Type: CWE-843
Base Score: 6.8
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 8.8
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 2.8
Severity: HIGH