CVE-2026-82450CWE-434unrestricted-file-upload

CVE-2026-82450

High · published August 29, 2026

CVSS v3.1
8.8
EPSS
1%
Percentile
62.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.8 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
8.7 · 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
EPSS
0.00999 · 62.4th percentile
Weakness
CWE-434 · Unrestricted Upload of File with Dangerous Type
Published
2026-08-29T18:16Z
References (3)
https://github.com/BookStackApp/BookStack · [email protected]https://github.com/BookStackApp/BookStack/commit/e210cc32e4cbb1efeae5c5c9d0fef8e3c6a752e6 · [email protected]https://www.vulncheck.com/advisories/bookstack-before-26.05.4-remote-code-execution-via-book-cover · [email protected]
EPSS history
Timeline
  • 30 AUG 16:19Z
    EPSS moved — → 1%
    epss
  • 29 AUG 13:47Z
    BookStack before 26.05.4 Remote Code Execution via Book Cover
    cvelistv5