Disclosure of user names via admin bulk action views in wagtail

Wagtail is an open source content management system built on Django. A user with a limited-permission editor account for the Wagtail admin can make a direct URL request to the admin view that handles bulk actions on user accounts. While authentication rules prevent the user from making any changes, the error message discloses the display names of user accounts, and by modifying URL parameters, the user can retrieve the display name for any user. The vulnerability is not exploitable by an ordinary site visitor without access to the Wagtail admin. Patched versions have been released as Wagtail 4.1.8 (LTS), 5.0.5 and 5.1.3. The fix is also included in Release Candidate 1 of the forthcoming Wagtail 5.2 release. Users are advised to upgrade. There are no known workarounds for this vulnerability.