"Clear History and Website Data" did not clear the history. The issue was addressed with improved data deletion. This issue is fixed in macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave, iOS 14.3 and iPadOS 14.3, tvOS 14.3. A user may be unable to fully delete browsing history.
The bubblewrap sandbox of WebKitGTK and WPE WebKit, prior to 2.28.3, failed to properly block access to CLONE_NEWUSER and the TIOCSTI ioctl. CLONE_NEWUSER could potentially be used to confuse xdg-desktop-portal, which allows access outside the sandbox. TIOCSTI can be used to directly execute commands outside the sandbox by writing to the controlling terminal's input buffer, similar to CVE-2017-5226.
A use-after-free issue exists in WebKitGTK before 2.28.1 and WPE WebKit before 2.28.1 via crafted web content that allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash).
WebKitGTK through 2.26.4 and WPE WebKit through 2.26.4 (which are the versions right before 2.28.0) contains a memory corruption issue (use-after-free) that may lead to arbitrary code execution. This issue has been fixed in 2.28.0 with improved memory handling.
Webkit-GTK 2.x (any version with HTML5 audio/video support based on GStreamer) allows remote attackers to trigger unexpectedly high sound volume via malicious javascript. NOTE: this WebKit-GTK behavior complies with existing W3C standards and existing practices for GNOME desktop integration.