CVE-2026-86285 Details
Description
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.
A broken access control vulnerability has been identified in BookStack versions prior to 26.05.2. The issue resides in the Attachment Edit Endpoint, specifically within the AttachmentController's getUpdateForm function. The vulnerability allows users with page-update rights, but not page-view rights, to access attachment names and external URLs of link-type attachments from pages they cannot view. This exploitation is possible because the attachment is retrieved by ID without checking if the user has permission to view the associated page.
Users are advised to update to BookStack version 26.05.3 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 7, 2026CISA-ADP
Assessed Sep 9, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://ashutosh-jena.in/blog/broken-access-control-in-bookstack-how-a-missing-permission-check-leaked-attachment-data | [email protected] | ExploitTechnical Analysis |
| https://codeberg.org/bookstack/bookstack/commit/4e406c41c4c8060a5795e74c66fb96362e54f400 | [email protected] | Source CodeVendor |
| https://vuldb.com/cve/CVE-2026-86285 | [email protected] | AdvisoryPermission Required |
| https://vuldb.com/submit/905693 | [email protected] | Issue TrackingPermission Required |
| https://vuldb.com/vuln/399445 | [email protected] | AdvisoryPermission Required |
| https://vuldb.com/vuln/399445/cti | [email protected] | AdvisoryPermission Required |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-266 | Incorrect Privilege Assignment | [email protected] |
| CWE-284 | Improper Access Control | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| BookStack | <= 26.05.2 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 9, 2026 | CVE Modified | CISA-ADP |
| Sep 7, 2026 | New CVE Received | [email protected] |