Mozilla: Iframe contents could be rendered outside the iframe

The Mozilla Foundation Security Advisory describes this flaw as: Use tables inside of an iframe, an attacker could have caused iframe contents to be rendered outside the boundaries of the iframe, resulting in potential user confusion or spoofing attacks...

CVE-2021-23996

By utilizing 3D CSS in conjunction with Javascript, content could have been rendered outside the webpage's viewport, resulting in a spoofing attack that could have been used for phishing or other attacks on a user. This vulnerability affects Firefox 88...