CVE-2020-5256: Bookstackapp Bookstack

High severity, CVSS 8.8. EPSS: 2% chance of exploitation in the next 30 days.

BookStack before version 0.25.5 has a vulnerability where a user could upload PHP files through image upload functions, which would allow them to execute code on the host system remotely. They would then have the permissions of the PHP process. This most impacts scenarios where non-trusted users are given permission to upload images in any area of the application. The issue was addressed in a series of patches in versions 0.25.3, 0.25.4 and 0.25.5. Users should upgrade to at least v0.25.5 to avoid this vulnerability.

Affected products

• Bookstackapp Bookstack: before 0.25.3 (fixed in 0.25.3)

Published 2020-03-09. Last modified 2026-06-17.