1815042 - Permanent private browsing mode leaks information to private storage from partitioning

Status: RESOLVED DUPLICATE of bug 1814733

(Core :: Privacy: Anti-Tracking, defect)

Description

[sworddragon2]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/109.0

Steps to reproduce:

1. In about:preferences#privacy configure Firefox to never store any history (to enable permanent private browsing mode).
2. Since this seems to be related to partitioning it might be needed to isolate cookies in about:preferences#privacy under custom tracking protection.
3. Go to https://itch.io/ and hover over the embeded YouTube video.

Actual results:

In the Firefox profile under \storage\default the directory https+++www.youtube.com^privateBrowsingId=1&partitionKey=%28https%2Citch.io%29 with some content in it is created.

Expected results:

Private storage should not have been touched as the above case reveals that the user visted https://itch.io/ and saw some YouTube content on it.

Additional information:

For a long time under about:preferences#privacy I noticed that over days/weeks the cache grows slowly about a few MiB in this timespan. I was never bothered about this since I thought this might be caused from some internal stuff Firefox might do - but maybe it is just from this leak (or both). I'm quite curious if sites could also use this to re-identify the user if he restarts Firefox.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Privacy: Anti-Tracking' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Tim Huang[:timhuang]]

Andrew, could this be related to the previous service worker's issues in PBM?

Comment 3

[Andrew Sutherland [:asuth] (he/him)]

See referenced bug.