Yesterday Mozilla released Firefox browser version 51. We just installed it in our browser cloud and it's now available to all users. You can now cross-browser test your designs, sites and JavaScript code in Firefox 51!

Cross-browser testing in Firefox 51

Try Firefox 51 in Browserling now!

Firefox 51 added support for FLAC (Free Lossless Audio Codec) playback. Better Tab Switching. Support for WebGL 2 and a warning that is displayed when a login page does not have a secure connection.

New Firefox 51 features:

  • Added Georgian (ka) and Kabyle (kab) locales.
  • Added support for FLAC (Free Lossless Audio Codec) playback.
  • A warning is displayed when a login page does not have a secure connection.
  • An even faster E10s. Tab Switching is better.
  • Improved reliability of browser data sync.
  • Added a zoom button in the URL bar: Displays percent above or below 100 percent when a user has changed the page zoom setting from the default. Lets users return to the default setting by clicking on the button.
  • Users can view passwords in the save password prompt before saving them.
  • Remove Belarusian (be) locale.
  • Firefox will save passwords even in forms that do not have "submit" events.
  • Improved video performance for users without GPU acceleration for less CPU usage and a better full screen experience.
  • Added support for WebGL 2, with advanced graphics rendering features like transform feedback, improved texturing capabilities, and a new sophisticated shading language.

Firefox 51 changes:

  • Updated to NSS 3.28.1.
  • Re-enabled E10s support for Russian (ru) locale.
  • Use 2D graphics library (Skia) for content rendering on Linux.

Firefox 51 developer tool updates include:

  • Network Monitor now shows a "Blocked" state for network requests.

Firefox 51 HTML, DOM, SVG, WebGL and JavaScript updates include:

  • IndexedDB version 2 implementation is now complete.
  • WebGL 2 is now enabled by default.
  • SVG now has tabindex attribute.
  • Css now has :indeterminate for <input type="radio">
  • <hr> elements can now be used as separators in <menu> elements.

Firefox 51 security fixes include:

  • Disclosure of local file existence through TRACK tag error messages.
  • Remove addons.mozilla.org CDN from whitelist for mozAddonManager.
  • Feed preview can expose privileged content errors and exceptions.
  • Memory safety bugs fixed in Firefox 51.
  • Memory corruption with transforms to create gradients in Skia.
  • Insecure communication methods in Developer Tools JSON viewer.
  • Data sent in multipart channels ignores referrer-policy response headers.
  • WebExtensions can use data: protocol to affect other extensions.
  • WebRTC can be used to generate a large amount of UDP traffic for DDOS attacks.
  • Excessive JIT code allocation allows bypass of ASLR and DEP.
  • Memory safety bugs fixed in Firefox 51 and Firefox ESR 45.7.
  • Content about: pages can load privileged about: pages.
  • Android location bar spoofing using fullscreen and JavaScript events.
  • WebExtensions can install additional add-ons via modified host requests.
  • Location bar spoofing with unicode characters.
  • Android location bar spoofing during scrolling.
  • Pointer and frame data leakage of Javascript objects.
  • Use-after-free with Media Decoder.
  • Use-after-free in XSL.
  • Use-after-free in Web Animations.
  • Weak references using multiple threads on weak proxy objects lead to unsafe memory usage.
  • Information disclosure via Proxy Auto-Config (PAC).
  • Certificate Viewer exporting can be used to navigate and save to arbitrary filesystem locations.
  • Potential use-after-free during DOM manipulations.

Unresolved Firefox 51 issues:

  • Crash with some older versions of Forcepoint/Websense.

Happy cross-browser testing in Firefox 51!