This release addresses a cross-site scripting (XSS) vulnerability in rich text fields. When saving the contents of a rich text field in the admin interface, Wagtail did not apply server-side checks to ensure that link URLs use a valid protocol. A malicious user with access to the admin interface could thus craft a POST request to publish content with javascript: URLs containing arbitrary code. The vulnerability is not exploitable by an ordinary site visitor without access to the Wagtail admin.
Many thanks to Kevin Breen for reporting this issue.
