Description
BookStack before 26.05.4 contains a broken access control vulnerability that allows authenticated API users with image-update or image-delete permissions to manipulate other users' avatars by exploiting missing content-type restrictions in the Image Gallery API endpoints. Attackers can supply a user avatar's ID to the API controller, which loads any image type without the web controller's gallery and drawio restrictions, and when the avatar's uploaded_to field matches a page ID accessible to the attacker, the authorization check passes allowing the attacker to rename, replace, or delete the target user's avatar without requiring user-management permission.
Published: 2026-08-24
Score: 5.3 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Mon, 24 Aug 2026 18:30:00 +0000

Type Values Removed Values Added
First Time appeared Bookstackapp
Bookstackapp bookstack
Vendors & Products Bookstackapp
Bookstackapp bookstack
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 24 Aug 2026 16:00:00 +0000

Type Values Removed Values Added
Description BookStack before 26.05.4 contains a broken access control vulnerability that allows authenticated API users with image-update or image-delete permissions to manipulate other users' avatars by exploiting missing content-type restrictions in the Image Gallery API endpoints. Attackers can supply a user avatar's ID to the API controller, which loads any image type without the web controller's gallery and drawio restrictions, and when the avatar's uploaded_to field matches a page ID accessible to the attacker, the authorization check passes allowing the attacker to rename, replace, or delete the target user's avatar without requiring user-management permission.
Title BookStack < 26.05.4 Broken Access Control via Image Gallery API
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L'}

cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N'}


Subscriptions

Bookstackapp Bookstack
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-24T17:20:18.693Z

Reserved: 2026-07-28T16:06:49.775Z

Link: CVE-2026-67204

cve-icon Vulnrichment

Updated: 2026-08-24T17:20:12.218Z

cve-icon NVD

Status : Received

Published: 2026-08-24T16:17:17.790

Modified: 2026-08-24T18:17:01.400

Link: CVE-2026-67204

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-24T18:15:06Z

Weaknesses