Referer Header should be disabled for new tabs
The referer header allows tracking when a link is opened in a new tab.
https://www.torproject.org/projects/torbrowser/design/ has valid reasons for not disabling referers alltogether.
However, explicit links that a user is expected to click very rarely fail when they are opened without referer. When they do, users can still open them in the original tab as a workaround. Even without stripping the referer, this is already necessary in some cases (e.g. certain Javascript links). Many users will already be trained to perform the workaround.
Leaving the referer in place when opening new tabs allows unexpected tracking across different tabs and undermines circuit isolation. With circuit isolation in place, the user expectation is that different tabs are isolated. For many users, the majority of tabs will be opened via 'open link in new tab' and users can potentially be tracked across long browsing sessions.
With referers in place, users are exposed to a much higher risk that accounts on different sites can be tied together, when they expected that tabs are fully isolated.
This referer stripping should at the very least be performed on the highest security setting.
Tor Browser Patch:
--- a/browser/base/content/utilityOverlay.js
+++ b/browser/base/content/utilityOverlay.js
@@ -358,7 +358,7 @@ function openLinkIn(url, where, params) {
case "tab":
w.gBrowser.loadOneTab(url, {
referrerURI: aReferrerURI,
- referrerPolicy: aReferrerPolicy,
+ referrerPolicy: Components.interfaces.nsIHttpChannel.REFERRER_POLICY_NO_REFERRER,
charset: aCharset,
postData: aPostData,
inBackground: loadInBackground,Trac:
Username: someone_else