A duplicate <code>SystemPrincipal</code> object could be created when parsing a non-system html document via <code>DOMParser::ParseFromSafeString</code>. This could have lead to bypassing web security checks. This vulnerability affects Firefox < 109.
USN-5816-1 fixed vulnerabilities in Firefox. The update introduced several minor regressions. This update fixes the problem. Niklas Baumstark discovered that a compromised web child process of Firefox could disable web security opening restrictions, leading to a new child process being spawned within the file:// context. Tom Schuster discovered that Firefox was not performing a validation check on GTK drag data. An attacker could potentially exploits this to obtain sensitive information. Various other issues were also addressed.
