CVE-2026-67204

Summary

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 Software

Weaknesses

• CWE-863: Incorrect Authorization

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

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

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