Earlier this year a major vulnerability called the WebRTC vulnerability was discovered in Windows machines running Chrome and Firefox. This vulnerability can compromise your privacy by allowing websites to see your true IPv6 address despite the use of a VPN. When using a VPN any site you visit should only see the IP address of the VPN’s exit server. This prevents them from correlating you with your visit with your geographic location, and building profiles based on your IP address. To test your system and see if your IP is leaking you can visit https://ipleak.net/.
Thankfully this vulnerability is very easy to correct in Firefox but it cannot be corrected through the “Options” dialogue. To correct it go to your URL bar in Firefox and type “about:config.” This will open a menu where power-users can make many adjustments to the application (many of these adjustments can be made through the Settings, but many cannot). Bypass the warning and scroll down to “media.peerconnection.enabled.” This setting is “true” by default. Double-click this line which will toggle the value to “false.” This is all that is required to turn off WebRTC and secure this vulnerability.
There are add-ons for Chrome (WebRTC Leak Prevent and ScriptSafe) that are intended to defeat the WebRTC vulnerability. It has been reported that these add-ons can be bypassed by a malicious adversary and should not be relied on. However, if you must use Chrome you should enable one of these add-ons.
For full protection use Firefox and adjust as described above. Using NoScript may also help mitigate this vulnerability.