A website could have obscured the full screen notification by using the file open dialog. This could have led to user confusion and possible spoofing attacks. *Note: This issue only affected macOS operating systems. Other operating systems are unaffected.* This vulnerability affects Firefox < 119, Firefox ESR < 115.4, and Thunderbird < 115.4.1.
https://www.mozilla.org/security/advisories/mfsa2023-47/
https://www.mozilla.org/security/advisories/mfsa2023-46/