What Changed in Gecko: Firefox 132
GeckoView EngineWhy This Matters
Gecko is the last truly independent browser engine — the only major alternative to Google’s Blink. Every Firefox release ripples through Tor Browser, LibreWolf, Mullvad Browser, and dozens of privacy-focused forks. Firefox 132 is a powerhouse release: 4K streaming arrives via PlayReady, Wide Color Gamut hits WebGL, the network stack gets post-quantum encryption, and developers gain fetchpriority for fine-grained resource loading. Here’s everything that changed.
CSS
The CSS story in 132 is about cleanup and correctness. text-emphasis-position now supports the auto value, aligning it with text-underline-position (bug 1919658).
More importantly, CSS Nested Declarations are now parsed in the correct order (bug 1918408). If you’ve been using CSS nesting and noticed subtle ordering bugs, this is the fix. The corresponding CSSNestedDeclarations JavaScript interface is also now available.
On the removal front, -moz-user-modify has been dropped in favor of the standard contenteditable attribute (bug 1920118).
JavaScript
Regular expression modifiers ((?ims-ims:...)) have shipped, allowing flag changes scoped to specific parts of a pattern (bug 1913752). This is a TC39 proposal that Gecko was among the first engines to implement.
Behind experimental flags, Promise.try() and JSON.parse with source access are available for testing — both are Stage 3 TC39 proposals likely to ship in a future release.
Web APIs
The biggest developer-facing addition is fetchpriority — now supported on <link>, <script>, <img> elements, the fetch() API, and the HTTP Link header. Set high, low, or auto to hint the browser about resource priority. Firefox maps these to HTTP/2 and HTTP/3 urgency parameters (bug 1854077).
requestVideoFrameCallback() lands on HTMLVideoElement, enabling per-frame video processing — essential for canvas painting, real-time analysis, and audio sync (bug 1919367).
MediaStreamTrack.getCapabilities() is now available, returning the full range of supported constraints for a media track (bug 1179084). And Notification.silent lets developers send system notifications without sound or vibration (bug 1809028).
WebGL gains Wide Color Gamut support through drawingBufferColorSpace and unpackColorSpace — P3 profiles in 8-bit are now live on Windows and macOS (bug 1885491).
The Permissions API now supports querying microphone and camera permissions, so apps can check access status before prompting users (bug 1609427).
Security & Privacy
Firefox 132 adds post-quantum key exchange for TLS 1.3 using ML-KEM 768 × X25519 (mlkem768x25519). This protects current connections against future quantum computing attacks — a “harvest now, decrypt later” defense (Firefox release notes).
Certificate Compression reduces TLS handshake size and speeds up connection establishment.
On the privacy side, all third-party cookies are now blocked when Enhanced Tracking Protection is set to Strict (bug 1918037). HTTP favicons that can’t be upgraded to HTTPS are also now blocked, continuing the mixed-content cleanup that started in Firefox 127.
HTTP/2 Server Push has been disabled by default and will likely be removed entirely — no other major browser supports it anymore (bug 1915848).
Performance
The WebRender pipeline now handles hardware-accelerated SVG filter primitives including feBlend, feColorMatrix, feGaussianBlur, feComposite, and 5 others. Graphics-heavy pages with SVG filters should see measurable rendering improvements.
Microsoft PlayReady DRM support is rolling out on Windows, enabling 1080p baseline and 4K Ultra HD streaming with less battery drain. This is a progressive rollout with key streaming partners.
The macOS session resume feature now automatically relaunches Firefox after a system restart (e.g., after OS updates).
Developer Tools
Console logging in service workers is functional again — console.log output now appears in the DevTools Console panel as expected. Remote USB debugging has also been restored: connect your phone via about:debugging and it will appear in the device list correctly.
The “Copy Without Site Tracking” option is now grayed out when no tracking parameters are detected, with expanded parameter support for LinkedIn and Shopee.
Bottom Line
Streaming enthusiasts get 4K via PlayReady and Wide Color Gamut WebGL. Web developers gain fetchpriority, requestVideoFrameCallback(), and fixed CSS nesting — tools that directly improve performance and code quality. Security teams should note the post-quantum TLS upgrade, which future-proofs connections today. And the Gecko ecosystem — Tor, LibreWolf, Mullvad — inherits stronger cookie blocking and certificate compression across the board.