CVE-2026-82450EPSS p61.6%

CVE-2026-82450CVE-2026-82450

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.

Scoring

CVSS 8.8 ()
VectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS1.00% probability of exploitation · percentile 61.6% · 2026-10-06T12:00:23Z
Last modified2026-08-31
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.