High 8.8Published Aug 29, 2026

CVE-2026-82450BookStack before 26.05.4 Remote Code Execution via Book Cover

Updated under an hour ago (2026-10-19 09:10 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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: 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-434
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Deferred
Record last updated: Oct 8, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

bookstackapp bookstack bookstackapp:bookstack (from the name)	before 26.05.4	CNA record

References

https://github.com/BookStackApp/BookStack/commit/e210cc32e4cbb1efeae5c5c9d0fef8e3c6a752e6patch
https://github.com/BookStackApp/BookStackproduct
https://www.vulncheck.com/advisories/bookstack-before-26.05.4-remote-code-execution-via-book-coverthird-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.