Multiple vulnerabilities have been discovered in Mozilla Firefox and Mozilla Firefox ESR, the most severe of which could allow for remote code execution. These vulnerabilities can be exploited if a user visits a specially crafted web page. Details of these vulnerabilities are as follows: 

• One user-after-free vulnerability exists when shutdown code for Web Worker was used. (CVE-2020-12387)

• Two sandbox escape vulnerabilities exist with Firefox's content processes that did not sufficiently lockdown access control. (CVE-2020-12388, CVE-2020-12389)

• One buffer overflow vulnerability exists wen parsing and validating SCTP chunks in WebRTC. (CVE-2020-6831)

• One security check vulnerability exits that could cause incorrect security checks with incorrect origin serialization of URLs with IPv6 (CVE-2020-12390)

• One vulnerability exits that allows for execution of blocked scripts for documents formed using data: URLs. (CVE-2020-12391)

• Two vulnerabilities exist within the 'Copy as cURL' feature within Firefox that can cause local file access and command injection. (CVE-2020-12393, CVE-2020-12392)

• One spoofing vulnerability exists within Firefox's location bar implementation. (CVE-2020-12394)

• Two memory corruption vulnerabilities exist that could cause memory corruption and execution of arbitrary code. (CVE-2020-12395, CVE-2020-12396) 

Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution in the context of the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.