CVE-2026-82450: Unrestricted Upload of File with Dangerous Type in bookstackapp bookstack
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.
CVE-2026-82450: Unrestricted Upload of File with Dangerous Type in bookstackapp bookstack
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.
CVSS v4.0
Score 8.7high
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-08-29T13:22:57.885Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a92e429acd9273b49d3585d
Added to database: 08/29/2026, 13:52:41 UTC
Last updated: 08/30/2026, 02:02:33 UTC
Views: 12
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