CVE-2026-84695

BookStack before 26.05.4 Stored XSS via Drawing Upload

Published Sep 2, 2026 CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title BookStack before 26.05.4 Stored XSS via Drawing Upload
First Time appeared Bookstackapp
Bookstackapp bookstack
Weaknesses CWE-79
CPEs cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:*
Vendors & Products Bookstackapp
Bookstackapp bookstack
References
Metrics cvssV3_1

{'score': 8.7, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Sep 2, 2026, 4:01 PM
Reserved
Sep 1, 2026, 11:24 PM
Status
Deferred
Published
Sep 2, 2026, 1:17 AM
Modified
Sep 8, 2026, 8:18 PM