What is CVE-2026-5484?

CVE-2026-5484 is a medium-severity vulnerability in Bookstackapp Bookstack, classified under Incorrect Privilege Assignment. CVSS score: 5.3/10. Published 2026-04-03.

How severe is CVE-2026-5484?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Privilege escalation in Bookstackapp Bookstack

CVE-2026-5484

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.

Published 2026-04-03 · last modified 2026-07-20.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.005 (43.8th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 44th percentile — 43.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002

Affected products

Bookstackapp Bookstack — versions 26.03, 26.03.1

Weakness classification (CWE)

References

vuldb.com/vuln/355091 (technical-description, vdb-entry)
vuldb.com/vuln/355091/cti (signature, permissions-required)
vuldb.com/submit/781762 (third-party-advisory)
github.com/Ghufran2/CVE-Bookstack/blob/main/Permission Bypass in Markdown Chapt… (exploit)
www.bookstackapp.com/blog/bookstack-release-v26-03-1/ (related)
github.com/BookStackApp/BookStack/commit/8a59895ba063040cc8dafd82e94024c406df3d… (patch)
github.com/BookStackApp/BookStack/releases/tag/v26.03.1 (patch)
github.com/BookStackApp/BookStack/ (product)

Frequently asked questions

What is CVE-2026-5484?: CVE-2026-5484 is a medium-severity vulnerability in Bookstackapp Bookstack, classified under Incorrect Privilege Assignment. CVSS score: 5.3/10. Published 2026-04-03.
How severe is CVE-2026-5484?: Medium severity. CVSS v3 base score is 5.3 out of 10.