Easy Firefox Fix of the Day: Disable HTTP3

If Firefox isn’t working for you right now (fails to load any site), try changing the about:config key of ‘network.http.http3.enabled’ to false (double-click).

If you want to verify whether Firefox HTTP3 is working, try this:

  1. Goto https://cloudflare-quic.com/
  2. Press F12 for the Developer Tools and open the Network tab.
  3. Right-click a column header and add a check to “Protocol” to add it.
  4. Click reload to see if HTTP3 is enabled.

Mozilla announced last year that HTTP3 would default to true.

Support for QUIC and HTTP/3 is now enabled by default in Firefox Nightly and Firefox Beta. We are planning to start rollout on the release in Firefox Stable Release 88. HTTP/3 will be available by default by the end of May [2021].

Early this morning a bug was investigated as users reported high CPU usage and pages not loading.

Our current suspicion is that a cloud provider or load balancer that fronts one of our own servers got an update that triggers an existing HTTP3 bug. Telemetry was first implicated because it’s one of the first services a normal Firefox configuration will connect to, but presumably the bug will trigger with any other connection to such a server (so disabling telemetry is pointless).

*** This is a Security Bloggers Network syndicated blog from flyingpenguin authored by Davi Ottenheimer. Read the original post at: https://www.flyingpenguin.com/?p=37674