CVE-2026-67204
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.
How to fix
- BookStackApp BookStack26.05.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| BookStackApp BookStack | v < 26.05.4 | 26.05.4 |
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