CVE-2026-67204 BookStack < 26.05.4 Broken Access Control via Image Gallery API
Authenticated users can modify or delete other users' avatars via the Image Gallery API due to missing authorization checks.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-67204?
CVE-2026-67204 is a medium-severity missing authorization vulnerability in BookStackApp BookStack, published on 24 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-863
Which versions are affected by CVE-2026-67204?
How do I fix CVE-2026-67204?
No fix has been published for CVE-2026-67204 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-67204 being exploited?
There is no known exploitation of CVE-2026-67204 in the wild and no public exploit code.
Sources
Also known as GHSA-v32j-vgqh-f22g.