BookStack before 26.05.4 contains a remote code execution vulnerability in the portable ZIP import functionality that allows users with Import Content and Create Books permissions to upload a PHP polyglot file as a book cover. Attackers can bypass image extension validation by embedding a PHP file with a .php filename in the ZIP archive, which is stored in the public web root and executed by unauthenticated requests.
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Fixes

Solution

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Workaround

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History

Sat, 29 Aug 2026 14:00:00 +0000

Type Values Removed Values Added
Description BookStack before 26.05.4 contains a remote code execution vulnerability in the portable ZIP import functionality that allows users with Import Content and Create Books permissions to upload a PHP polyglot file as a book cover. Attackers can bypass image extension validation by embedding a PHP file with a .php filename in the ZIP archive, which is stored in the public web root and executed by unauthenticated requests.
Title BookStack before 26.05.4 Remote Code Execution via Book Cover
First Time appeared Bookstackapp
Bookstackapp bookstack
Weaknesses CWE-434
CPEs cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:*
Vendors & Products Bookstackapp
Bookstackapp bookstack
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-29T13:47:53.312Z

Reserved: 2026-08-29T13:22:57.885Z

Link: CVE-2026-82450

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-29T14:16:37.930

Modified: 2026-08-29T14:16:37.930

Link: CVE-2026-82450

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-29T15:30:04Z

Weaknesses