CVE-2026-123820: Wagtail: Improper restriction handling on descendant collections in Documents and Images API

Wagtail is an open source content management system built on Django. Prior to 7.0.9, 7.3.4, 7.4.3, and 8.0rc2, the Wagtail Documents and Images API V2 excludes directly restricted collections but fails to exclude their descendant collections, even though descendants inherit ancestor view restrictions. An API user can therefore list the filenames and names of documents and images stored in descendant collections that should remain private. This issue is fixed in versions 7.0.9, 7.3.4, 7.4.3, and 8.0rc2.