It was possible to cause the browser to enter fullscreen mode without displaying the security UI; thus making it possible to attempt a phishing attack or otherwise confuse the user. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
[
{
"product": "Firefox",
"vendor": "Mozilla",
"versions": [
{
"status": "affected",
"version": "< 83"
}
]
},
{
"product": "Firefox ESR",
"vendor": "Mozilla",
"versions": [
{
"status": "affected",
"version": "< 78.5"
}
]
},
{
"product": "Thunderbird",
"vendor": "Mozilla",
"versions": [
{
"status": "affected",
"version": "< 78.5"
}
]
}
]