June in Servo: real world compat, media queries, SharedWorker, and more

Servo 0.4.0, released in June 2026, contains 558 commits, marking a record for the project. This update includes several new web platform features and security improvements. Servo is steadily growing, with over four times the commits compared to its start in September 2023.

The update introduces changes that affect users, developers, embedders, or other groups, with observable differences made by the changes. Many real-world websites, such as Google Photos and Cash Converters, continue to work well in Servo 0.4.0. However, some websites have interactivity issues that need attention.

Servo's JS runtime, SpiderMonkey 140.11.0, has fixed several security bugs, including CVE-2026-8388, CVE-2026-8391, CVE-2026-8974, CVE-2026-8975, and MFSA 2026-48. Additionally, RSA and ML-DSA operations in SubtleCrypto now perform modular exponentiation and decompose steps in constant time, respectively, addressing the Marvin Attack and RUSTSEC vulnerabilities.

Improvements in layout correctness have made many websites, including lichess.org, Zulip, and Speedtest.net, more readable. The 'attr()' feature is now more powerful and can be used anywhere, not just in 'content'. WebGPU support has improved, and support for accessibility and text selection has started to be implemented.

Servo's webview support has been enhanced, allowing for drag and drop functionality and better performance on the desktop version. Moreover, the desktop version now enters fullscreen mode on the monitor containing the window. These updates make Servo an increasingly powerful and reliable browser option.