CVE-2026-116020: Auth Bypass (CVSS 5.4)

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permissions can enumerate sequential attachment IDs to download, rename, relink, or replace files on another user's unpublished draft pages.

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CVSS v3.1 Score

5.4

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Weakness Type (CWE)

CWE-863 Incorrect Authorization

References

Other 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

Frequently Asked Questions

What is CVE-2026-116020? +

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permissions can enumerate sequential attachment IDs to download, rename, relink, or replace files on another user's unpublished draft pages. It has a CVSS v3.1 base score of 5.4 (MEDIUM).

How severe is CVE-2026-116020? +

CVE-2026-116020 has a CVSS v3.1 score of 5.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-116020? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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