CVE-2026-84695

EUVD-2026-69786
BookStack before 26.05.4 contains a stored cross-site scripting vulnerability in the drawing upload endpoint that accepts unvalidated base64 content and stores it without content inspection. Attackers with editor permissions can upload SVG files containing scripts that execute in administrator browsers when accessed through the image gallery API without content-type validation or CSP headers.
Cross-site Scripting
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
8.7 HIGH
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 16.91%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
bookstackappbookstack
𝑥
< 26.5.4
CNA
Common Weakness Enumeration
References
https://github.com/BookStackApp/BookStack
https://github.com/BookStackApp/BookStack/blob/v26.05.3/app/Uploads/ImageService.php
https://github.com/BookStackApp/BookStack/commit/ac0348a79f3ddd004ca87703948cb9c7d19a420a
https://github.com/BookStackApp/BookStack/releases/tag/v26.05.4
https://www.bookstackapp.com/blog/bookstack-release-v26-05-4/
https://www.vulncheck.com/advisories/bookstack-before-26.05.4-stored-xss-via-drawing-upload