# 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.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Apr 2026
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-h29h-hh8g-q4wh

## 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.

Weakness: CWE-284 (Improper Access Control), CWE-266 (Incorrect Privilege Assignment)

## 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.

## Is CVE-2026-5484 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5484 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5484 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5484 exists.

Affected product: BookStackApp BookStack. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-5484/ (Markdown: https://insights.sbomify.com/CVE-2026-5484/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5484
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5484
- OSV: https://osv.dev/vulnerability/CVE-2026-5484

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5484/
Summaries are generated and may contain mistakes; the official description above is the record.