TI-2026-04803 Aliases CVE-2026-5484 GHSA-h29h-hh8g-q4wh

BookStackApp BookStack Chapter Export ExportFormatter.php chapterToMarkdown access control

HIGH 70CWE-266Published 2026-04-03 · Updated 2026-04-08

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Privilege escalation, Security bypass
Confidentiality · integrity · availability: Low · None · None
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-266 and CWE-284.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00334 26th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by the CNA

Fix Fixed BookStack (BookStackApp): 26.03.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
bookstackapp	BookStack	26.03	26.03.1	Patch available	CNA

BookStack Vendorbookstackapp Affected 26.03 Fixed in 26.03.1 Patch available CNA

CPE names CNA · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:bookstackapp:bookstack::::::::	—	—	bookstackapp

cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:* Versions — — ·bookstackapp

Remediation

Fix · CNA BookStack (BookStackApp) Fixed in 26.03.1

Timeline

2026-10-02 Threatist record created from CVE-2026-5484
2026-10-03 Alias added: GHSA-h29h-hh8g-q4wh

References

Exploit 1

https://github.com/Ghufran2/CVE-Bookstack/blob/main/Permission%20Bypass%20in%20Markdown%20Chapter%20Export

Patch 2

Other 2

TI-2021-02995 Improper Access Control in bookstackapp/bookstack CVSS 3.1CRITICAL 9.8
TI-2023-04263 Server-Side Request Forgery (SSRF) in bookstackapp/bookstack CVSS 3.1LOW 2.4
TI-2026-60332 BookStack < 26.05.5 Authentication Bypass via Social Login Provider Confusion CVSS 4.0CRITICAL 9.1
TI-2026-56847 BookStack before 26.05.4 Remote Code Execution via Book Cover CVSS 4.0HIGH 8.7
TI-2020-04312 Remote Code Execution Through Image Uploads in BookStack CVSS 3.1HIGH 8.8
TI-2026-58223 BookStack before 26.05.4 Stored XSS via Drawing Upload CVSS 4.0CRITICAL 9.3

See all 26 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences