Consider releasing Tails 4.12.1 with Tor Browser 10.0.4
Tor Browser 10.0.4 upgrades to Firefox ESR 78.4.1, which fixes https://www.mozilla.org/en-US/security/advisories/mfsa2020-49/.
People using the Safer or Safest security level of Tor Browser are not affected because the feature of JavaScript that is affected (the just-in-time compilation) is disabled in these security levels.
Edited by sajolida