CVE-2026-84695 PUBLISHED

BookStack before 26.05.4 Stored XSS via Drawing Upload

Assigner: VulnCheck
Reserved: 01.09.2026 Published: 02.09.2026 Updated: 02.09.2026

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 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
CVSS Score: 9.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	High
Attack Complexity	Low	Integrity	High	Integrity	High
Attack Requirements	None	Availability	None	Availability	None
Privileges Required	Low
User Interaction	Passive

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
CVSS Score: 8.7

Attack Vector	Network	Scope	Changed
Attack Complexity	Low	Confidentiality Impact	High
Privileges Required	Low	Integrity Impact	High
User Interaction	Required	Availability Impact	None

CVSS 3.1

Product Status

Vendor	bookstackapp
Product	bookstack
Versions	Default: unaffected affected from 0 to 26.05.4 (excl.) Version 26.05.4 is unaffected

Credits

Emanuele Cervelli finder

References

Problem Types

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CWE