If the user added a security exception for an invalid TLS certificate, opened an ongoing TLS connection with a server that used that certificate, and then deleted the exception, Firefox would have kept the connection alive, making it seem like the certificate was still trusted. This vulnerability affects Firefox < 107.
[
{
"vendor": "Mozilla",
"product": "Firefox",
"versions": [
{
"version": "unspecified",
"lessThan": "107",
"status": "affected",
"versionType": "custom"
}
]
}
]