---
id: CVE-2026-5484
title: A weakness has been identified in BookStackApp BookStack up to 26.03
summary: >-
  A weakness has been identified in BookStackApp BookStack up to 26.03. Affected
  is the function chapterToMarkdown of the file app/Exports/ExportFormatter.php
  of the component Chapter Export Handler. Executing a manipulation of the
  argumen…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-266
  - CWE-284
published: '2026-04-03'
updated: '2026-07-20'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-5484'
references:
  - url: 'https://github.com/BookStackApp/BookStack/'
    label: cna@vuldb.com
  - url: >-
      https://github.com/BookStackApp/BookStack/commit/8a59895ba063040cc8dafd82e94024c406df3d04
    label: cna@vuldb.com
  - url: 'https://github.com/BookStackApp/BookStack/releases/tag/v26.03.1'
    label: cna@vuldb.com
  - url: >-
      https://github.com/Ghufran2/CVE-Bookstack/blob/main/Permission%20Bypass%20in%20Markdown%20Chapter%20Export
    label: cna@vuldb.com
  - url: 'https://vuldb.com/submit/781762'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/vuln/355091'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/vuln/355091/cti'
    label: cna@vuldb.com
  - url: 'https://www.bookstackapp.com/blog/bookstack-release-v26-03-1/'
    label: cna@vuldb.com
tags:
  - nvd
epss: 0.00322
epssPercentile: 0.25443
ingestedAt: '2026-07-21T16:51:40.602Z'
---

## Overview

A weakness has been identified in BookStackApp BookStack up to 26.03. Affected is the function chapterToMarkdown of the file app/Exports/ExportFormatter.php of the component Chapter Export Handler. Executing a manipulation of the argument pages can lead to improper access controls. It is possible to launch the attack remotely. The exploit has been made available to the public and could be used for attacks. Upgrading to version 26.03.1 is able to address this issue. This patch is called 8a59895ba063040cc8dafd82e94024c406df3d04. It is advisable to upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.