Fifteen years after its initial release, Waterfox continues moving forward at a steady pace. Version 6.6.12 of the Firefox fork, available since April 20, patches security vulnerabilities documented in Mozilla’s MFSA 2026-32 advisory and builds on the native ad blocking introduced in 6.6.11, which remains officially in preview.

Custom Filter List Manager

The most tangible improvement is a dedicated panel for managing external filter lists. You can now add and remove custom filter list URLs directly from the interface, instead of relying solely on built-in lists. The main filter list screen now includes a search bar, a manual refresh button, a menu to set update intervals (from 4 hours to 7 days), and information on when each list was last updated and when the next refresh is due.

Smarter Logic and Tighter Filtering

Each filter list now respects its own Expires value instead of following a uniform 12-hour refresh cycle for everything. Error handling has improved, and inputs are sanitized before being passed to the engine.

Cosmetic filtering, which hides page elements even when they aren’t blocked at the network level, is now more reliable. CSS injection only happens on HTML pages, not on XML or plain text; DOM analysis is capped to avoid slowdowns; and CSS rules are inserted directly rather than reconstructing the entire stylesheet each time.

Detection of conflicting ad-blocking extensions has been tightened. It now relies only on known extension IDs, dropping the old name and description matching that triggered false positives on unrelated extensions.

If you want to track the evolution of native blocking, follow the feedback thread on GitHub.