Medium severity · published Apr 3, 2026
CVE-2026-5484
BookStackApp BookStack Chapter Export ExportFormatter.php chapterToMarkdown access control
5.3
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 25% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BO
BookStack · BookStackApp
26.03 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-5484
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-5484
github.com
https://github.com/BookStackApp/BookStack/
github.com
https://github.com/BookStackApp/BookStack/commit/8a59895ba063040cc8dafd82e94024c406df3d04
github.com
https://github.com/BookStackApp/BookStack/releases/tag/v26.03.1
github.com
https://github.com/Ghufran2/CVE-Bookstack/blob/main/Permission%20Bypass%20in%20Markdown%20Chapter%20Export
vuldb.com
https://vuldb.com/submit/781762
vuldb.com
https://vuldb.com/vuln/355091
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