CVE-2026-67204

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.

CVSS v3 5.4 MEDIUM

5.4^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.5

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://codeberg.org/bookstack/bookstack/releases/tag/v26.05.4
https://github.com/BookStackApp/BookStack/releases/tag/v26.05.4
https://www.bookstackapp.com/blog/bookstack-release-v26-05-4/
https://www.vulncheck.com/advisories/bookstack-broken-access-control-via-image-gallery-api

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-24 16:17

Updated : 2026-08-24 18:17

NVD link : CVE-2026-67204

Mitre link : CVE-2026-67204

CVE.ORG link : CVE-2026-67204

JSON object : View

Products Affected

No product.

CWE

CWE-863

Incorrect Authorization

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