LinuxServer Changes:
Make APP_URL var required (upstream changes).
bookstack Changes:
Security Release
This release addresses an issue where page content could be visible to those without permission via the export options. The content of pages made non-viewable to a user via permissions, within a visible parent, could be seen via the plaintext export option. Before v0.30.6 this would have applied only to scenarios where all pages within the chapter were made non-visible. In v0.30.6 this would make all pages within the chapter visible.
Further details can be found in the vulnerability report.