CVE-2026-84695: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in bookstackapp bookstack
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.
CVE-2026-84695: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in bookstackapp bookstack
Description
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.
CVSS v4.0
Score 9.3critical
Affected software
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Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-01T23:24:15.911Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a977a61acd9273b49923c2c
Added to database: 09/02/2026, 01:22:41 UTC
Last updated: 09/02/2026, 02:07:08 UTC
Views: 5
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