CVE-2021-4026: Bookstackapp Bookstack

Medium severity, CVSS 4.3. EPSS: 0.9% chance of exploitation in the next 30 days.

bookstack is vulnerable to Improper Access Control

Affected products

• Bookstackapp Bookstack: before 21.11.2 (fixed in 21.11.2)

Published 2021-11-30. Last modified 2026-06-17.