LinuxServer Changes:
Rebase to alpine 3.17 with php8.1.
bookstack Changes:
Security Release
This is a security release that addresses a potential vulnerability in PDF generation that could be used to make server-side requests or run potential other PHP code.
Upgrade is advised where untrusted users have permission to create page content in your instance.
From testing, it appears that successful exploitation of this would require either the disabling of BookStack default security options, or access to the host machine system, but out of caution we're advising upgrade in any environment as specified above.