CVE-2026-82450
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.
- Published Aug 29, 2026
- CVSS 8.7 high
- 1.0% chance of exploitation in the next 30 days (EPSS)
- A fix is available