CVE-2026-126811

EUVD-2026-124026
BookStack before 26.09.3 contains an incorrect authorization vulnerability that allows authenticated users to access other users' unpublished draft page images by checking only PageView permission without draft status. Attackers can read drawio data via the base64 endpoint or rename, replace, or delete draft images by sequential ID to disclose or tamper with unpublished work.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
5.4 MEDIUM
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).
VendorProductVersionSource
bookstackappbookstack
𝑥
< 26.9.3
CNA
Common Weakness Enumeration
References
https://codeberg.org/bookstack/bookstack/commit/4fec06236cbfb314fd72c1b3614c7c50162fb41c
https://codeberg.org/bookstack/bookstack/commit/926e16a23f346be47d44746d14cba40cb355cbe1
https://codeberg.org/bookstack/bookstack/releases/tag/v26.09.3
https://github.com/BookStackApp/BookStack/blob/v26.09.2/app/Uploads/Controllers/DrawioImageController.php#L82-L92
https://github.com/BookStackApp/BookStack/blob/v26.09.2/app/Uploads/Controllers/ImageController.php#L159-L169
https://github.com/BookStackApp/BookStack/commit/926e16a23f346be47d44746d14cba40cb355cbe1
https://github.com/BookStackApp/BookStack/releases/tag/v26.09.3
https://github.com/fishtankyu/bookstack-draft-image-idor-advisory.md
https://www.bookstackapp.com/blog/bookstack-release-v26-09-3/
https://www.vulncheck.com/advisories/bookstack-before-26.09.3-incorrect-authorization-via-image-and-drawio-endpoints