If an attacker is able to alter specific about:config values (for example malware running on the user’s computer), the Devtools remote debugging feature could have been enabled in a way that was unnoticable to the user. This would have allowed a remote attacker (able to make a direct network connection to the victim) to monitor the user’s browsing activity and (plaintext) network traffic. This was addressed by providing a visual cue when Devtools has an open network socket. This vulnerability affects Firefox < 87.
[
{
"product": "Firefox",
"vendor": "Mozilla",
"versions": [
{
"lessThan": "87",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
}
]