Update on what happened in WebKit in the week from September 29 to October 6.
Another exciting weekful of updates, this time we have a number of fixes on MathML, content secutiry policy, and Aligned Trusted types, public API for WebKitWebExtension has finally been added, and fixed enumeration of speaker devices. In addition to that, there's ongoing work to improved compatibility for broken AAC audio streams in MSE, a performance improvement to text rendering with Skia was merged, and fixed multi-plane DMA-BUF handling in WPE. Last but not least, The 2026 edition of the Web Engines Hackfest has been announced! It will take place from June 15th to the 17th.
Cross-Port 🐱
Fixed rendering for unknown elements in MathML.
Fixed incorrect parsing of malformed require-trusted-types-for CSP directive.
Align reporting of Trusted Types violations with spec in case of multiple Content-Security-Policy headers.
Aligned Trusted Types event handler namespace checks with an update to the specification.
Fixed some incorrect handling of null or undefined policy values in Trusted Types.
On the WebExtensions front, the WebKitWebExtension API has finally been added, after porting some more code from Objective-C code to C++.
Improved alignment with MathML Core by making mfenced, semantics and maction render like an mrow, ignoring the subscriptshift/superscriptshift legacy attributes and cleaning the User-Agent stylesheet to more closely match the spec.
Multimedia 🎥
GStreamer-based multimedia support for WebKit, including (but not limited to) playback, capture, WebAudio, WebCodecs, and WebRTC.
Speaker device enumeration has been fixed to properly enumerate ALSA PCM devices, while improving audio output device handling in general.
Improved compatibility for broken AAC audio streams in MSE is currently in review.
JavaScriptCore 🐟
The built-in JavaScript/ECMAScript engine for WebKit, also known as JSC or SquirrelFish.
In JavaScriptCore's implementation of Temporal, improved the precision of addition and subtraction on Durations.
In JavaScriptCore's implementation of Temporal, improved the precision of calculations with the total() function on Durations. This was joint work with Philip Chimento.
In JavaScriptCore's implementation of Temporal, continued refactoring addition for Durations to be closer to the spec.
Graphics 🖼️
Landed a patch to build a SkTextBlob when recording DrawGlyphs operations for the GlyphDisplayListCache, which shows a significant improvement in MotionMark “design” test when using GPU rendering.
WPE WebKit 📟
WPE Platform API 🧩
New, modern platform API that supersedes usage of libwpe and WPE backends.
Improved wpe_buffer_import_to_pixels() to work correctly on non-linear and multi-plane DMA-BUF buffers by taking into account their modifiers when mapping the buffers.
Community & Events 🤝
The 2026 edition of the Web Engines Hackfest has been announced, and it will take place from June 15th to the 17th.
That’s all for this week!
