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.

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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'}


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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: 2026-08-24T20:00:04Z

Weaknesses