---
id: CVE-2026-86285
title: A vulnerability was detected in BookStack up to 26.05.2
summary: >-
  A vulnerability was detected in BookStack up to 26.05.2. Affected by this
  issue is the function AttachmentController::getUpdateForm of the file
  app/Uploads/Controllers/AttachmentController.php of the component Attachment
  Edit Endpoint. T…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-266
  - CWE-284
product: BookStack
affected:
  - BookStack 26.05.0
  - BookStack 26.05.1
  - BookStack 26.05.2
published: '2026-09-07'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T15:17:16.283'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86285'
references:
  - url: >-
      https://ashutosh-jena.in/blog/broken-access-control-in-bookstack-how-a-missing-permission-check-leaked-attachment-data
    label: cna@vuldb.com
  - url: >-
      https://codeberg.org/bookstack/bookstack/commit/4e406c41c4c8060a5795e74c66fb96362e54f400
    label: cna@vuldb.com
  - url: 'https://vuldb.com/cve/CVE-2026-86285'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/submit/905693'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/vuln/399445'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/vuln/399445/cti'
    label: cna@vuldb.com
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-09T14:20:10.802700Z'
epss: 0.00222
epssPercentile: 0.13023
ingestedAt: '2026-09-08T15:33:26.975Z'
---

## Overview

A vulnerability was detected in BookStack up to 26.05.2. Affected by this issue is the function AttachmentController::getUpdateForm of the file app/Uploads/Controllers/AttachmentController.php of the component Attachment Edit Endpoint. The manipulation of the argument ID results in improper access controls. The attack may be launched remotely. The exploit is now public and may be used. The patch is identified as 4e406c41c4c8060a5795e74c66fb96362e54f400. It is advisable to implement a patch to correct this issue.

## Remediation

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