Conclusion of: firefox cannot connect to any website, other browsers can?

[Keith]

On 1/14/22 7:26 AM, Colin Watson wrote:
> On Fri, Jan 14, 2022 at 10:49:40AM +0100, M. Fioretti wrote:
>> On Fri, Jan 14, 2022 09:40:50 AM +0000, Colin Law wrote:
>>> On Fri, 14 Jan 2022 at 05:49, M. Fioretti <mfioretti at nexaima.net> wrote:
>>>> In my case, the problem disappeared by itself the SECOND, or maybe
>>>> third time I quit and restarted Firefox, restarting it once did not do
>>>> anything (still running version 95.01).
>>>
>>> Had you tried clearing the cache (via the menus)? If you had to
>>> restart multiple times then that makes a cache issue most likely.
>>
>> Hi Colin,
>> no, I did not do that. It just did not come to my mind. But yes, you
>> are most likely right.
>
> Much more likely, based on what I'm reading the Mozilla bug report: it
> was a latent bug in Firefox's HTTP/3 implementation triggered by a
> server-side change, and the server-side change was rolled back.  Caches
> don't appear to be relevant.
>

So the vulnerability in Firefox is still present, it just won't be
triggered by connecting to Mozilla servers. Disabling HTTP/3 seems the
prudent thing to do until a Firefox update is released fixing the bug.

Assuming the codebases share the same networking implementation, it's
fortuitous that HTTP/3 is disabled by default in Thunderbird (at least
on Focal). Otherwise it would have been more than just browsers affected.

--
Keith