CVE-2026-5484 BookStackApp BookStack Chapter Export ExportFormatter.php chapterToMarkdown access control
Attackers can bypass access controls in the chapter export function to read unauthorized data in BookStack.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-5484?
CVE-2026-5484 is a medium-severity missing authorization vulnerability in BookStackApp BookStack, published on 3 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A weakness has been identified in BookStackApp BookStack up to 26.03. Affected is the function chapterToMarkdown of the file app/Exports/ExportFormatter.php of the component Chapter Export Handler. Executing a manipulation of the argument pages can lead to improper access controls. It is possible to launch the attack remotely. The exploit has been made available to the public and could be used for attacks. Upgrading to version 26.03.1 is able to address this issue. This patch is called 8a59895ba063040cc8dafd82e94024c406df3d04. It is advisable to upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.
Which versions are affected by CVE-2026-5484?
How do I fix CVE-2026-5484?
No fix has been published for CVE-2026-5484 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-5484 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5484 exists.
Sources
Also known as GHSA-h29h-hh8g-q4wh.