CVE-2026-116020: BookStack before 26.09.2 Incorrect Authorization via AttachmentController on Draft Pages
BookStack before 26.09.2 contains an incorrect authorization vulnerability in AttachmentController that allows authenticated users to access other users' draft page attachments by ID. Attackers with attachment permissions can enumerate sequential attachment IDs to download, rename, relink, or replace files on another user's unpublished draft pages.
Affected Software
Event History
Frequently Asked Questions
Who can exploit this issue?
An authenticated BookStack user with attachment permissions can exploit it. The user must be able to identify or enumerate attachment IDs, which are described as sequential.
Are unpublished draft pages affected?
Yes. The authorization flaw exposes attachments associated with other users' unpublished draft pages, rather than being limited to attachments on published content.
What could an attacker do with an accessible attachment?
An attacker can download, rename, relink, or replace files attached to another user's draft page. This can affect the confidentiality and integrity of draft attachments.
Which versions need remediation?
BookStack versions before 26.09.2 are affected. Updating to version 26.09.2 or later addresses the stated affected-version range.