CVE-2026-82450
HIGH
NVD
CVSS Score
8.8
Severity
HIGH
Published
Aug 29, 2026
Vendor
unknown
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.