Docmost is open-source collaborative wiki and documentation software. Prior to 0.90.1, an authenticated workspace member who does not belong to a private space can call the transclusion / sync-block lookup API with a known sourcePageId and transclusionId pair because the lookup does not enforce private space membership before resolving the source page. The API can return confidential sync-block content and source page metadata even though the normal page APIs deny access to the same page. This issue is fixed in version 0.90.1.
https://github.com/docmost/docmost/security/advisories/GHSA-5vhf-cgf2-c9cq
https://github.com/docmost/docmost/releases/tag/v0.90.1
https://github.com/docmost/docmost/commit/830b5b4d458a1302f42c8b68bff9ff559f6eb342