Mozilla Firefox Quantum V66.0.5 May 2026

The primary fix in v66.0.5 addressed a remaining issue where web extensions were still disabled for users with a master password set.

Allows users to authenticate on websites using facial recognition or fingerprints on Windows 10. System Requirements Firefox 66.0.5 System Requirements Mozilla Firefox Quantum v66.0.5

Prevents web pages from "jumping" while images and advertisements load. The primary fix in v66

Automatically prevents websites from playing sound-enabled media. Mozilla Firefox Quantum v66.0.5