CVE-2026-67204: BookStack < 26.05.4 Broken Access Control via Image Gallery API
BookStackApp · BookStack
Fixed in 26.05.4 · Affected: BookStackApp before 26.05.4 · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 36% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- BookStackApp · BookStackbefore 26.05.4
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- BookStackApp
- Published
- August 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-67204 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.