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.

Mozilla Firefox Quantum v66.0.5, released on May 7, 2019, was a critical point update primarily focused on resolving a significant bug that caused browser extensions to be disabled. Mozilla Firefox Quantum v66.0.5

Allows users to authenticate on websites using facial recognition or fingerprints on Windows 10. System Requirements Firefox 66.0.5 System Requirements The primary fix in v66

As part of the broader Firefox 66 release, this version includes: released on May 7

Prevents web pages from "jumping" while images and advertisements load.

Automatically prevents websites from playing sound-enabled media.

A new ability to search through all open tabs via the tab overflow menu.