[tbb-bugs] #16920 [Tor Browser]: Referer Header should be disabled for new tabs

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#16920: Referer Header should be disabled for new tabs
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 Reporter:  someone_else  |          Owner:  tbb-team
     Type:  defect        |         Status:  new
 Priority:  normal        |      Milestone:
Component:  Tor Browser   |        Version:
 Keywords:                |  Actual Points:
Parent ID:                |         Points:
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 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,
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16920>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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