What’s Vulnerable › Vulnerabilities

CVE-2026-116020: BookStack before 26.09.2 Incorrect Authorization via AttachmentController on Draft Pages

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-24 · updated 2026-10-26
• Weakness: CWE-863

Description

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permissions can enumerate sequential attachment IDs to download, rename, relink, or replace files on another user's unpublished draft pages.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 products

• bookstackapp/bookstack: before 26.09.2 — fixed in 26.09.2

How to fix

Upgrade to a fixed version: bookstackapp/bookstack 26.09.2. Check the vendor advisory for mitigations.

References

• https://codeberg.org/bookstack/bookstack/commit/fcadecccda706b4ecaf9ac3f8e27defe0ebe78ae
• https://codeberg.org/bookstack/bookstack/releases/tag/v26.09.2
• https://codeberg.org/bookstack/bookstack/src/tag/v26.09.1/app/Uploads/Controllers/AttachmentController.php
• https://www.bookstackapp.com/blog/bookstack-release-v26-09-2/
• https://www.vulncheck.com/advisories/bookstack-before-26.09.2-incorrect-authorization-via-attachmentcontroller-on-draft-pages

Get alerted when CVE-2026-116020 or the next vulnerability affects your stack