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State of the Tor Uplift

Currently, the Tor Browser is based on Firefox Extended Support Release (ESR); it lags behind stable releases by up to and only receives the subset of security backports deemed to be a high-enough priority.

The Tor Uplift project is an initiative to upstream all the Tor Browser’s patches into Firefox. Its goal is to make re-basing the Tor browser patches easy enough for the Tor Browser to track Firefox’s stable release channel. The Tor Uplift has been in progress for , with several of the Tor Browser’s biggest modifications successfully upstreamed (first-party isolation, fingerprinting resistance, and more robust proxy support).

On , Firefox 102 ESR was released. Today, on , Firefox 91 ESR will lose support. That gave a window of about three months (the duration of three Firefox stable releases) to re-base Tor Browser patches.

The first stable release of the Tor Browser based on 102 ESR hasn’t yet shipped (it’s close; an alpha version is available). Seven years into the Tor uplift, the Tor Project isn’t able to keep up with the Firefox ESR release calendar. I don’t think the Tor Uplift will succeed at getting the Tor Browser to track Firefox’s stable channel; at best, it’s keeping the Tor Browser from falling too far behind ESR.

Update : since Firefox 102 became the latest ESR, over since Firefox 91 ESR reached end-of-life, the latest stable Tor Browser desktop release (11.5.8) is still based on Firefox 91 ESR. Five CVEs fixes from v102 were backported a while ago, and another 13 were backported this week; the situation is worse on Android. It’s reasonable to assume that v91 has issues of its own that won’t be addressed. Until the v102-based 12.x hits stable: if you don’t use “safest”, you might want to re-consider that with this information in mind.