Docmost: Page export can include restricted same-space attachments through forged attachmentId

Docmost is open-source collaborative wiki and documentation software. From 0.70.0 until 0.80.1, a low-privileged authenticated user who can edit an exportable page can embed a forged attachmentId that belongs to a restricted page in the same space. Exporting the attacker-controlled page with includeAttachments=true causes the page export flow to read the restricted attachment from storage and include it in the returned ZIP archive even though direct file download denies access. This issue is fixed in version 0.80.1.