[tbb-bugs] #23216 [Applications/Tor Browser]: The `languagechange` event is noticeable on all open tabs

[Tor Bug Tracker & Wiki]

#23216: The `languagechange` event is noticeable on all open tabs
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     Reporter:  gk                        |      Owner:  tbb-team
         Type:  defect                    |     Status:  new
     Priority:  Medium                    |  Milestone:
    Component:  Applications/Tor Browser  |    Version:
     Severity:  Normal                    |   Keywords:  tbb-linkability
Actual Points:                            |  Parent ID:
       Points:                            |   Reviewer:
      Sponsor:                            |
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 It turns out that there is the `languagechange` event which is noticeable
 on all open tabs allowing to correlate activity of a user cross-domain and
 bypassing our unlinkability requirement.

 Now, triggering that one can't be done remotely and is probably not done
 very often. But still we should find a way to make it much less obvious to
 third party scripts that a particular user made language related changes
 and has been on website A, B, and C.

 Reported on HackerOne by tomvg.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23216>
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