Answer in brief
CVE-2026-82450 records a High severity (CVSS 8.7) vulnerability in BookStack before 26.05.4 Remote Code Execution via Book Cover. The current sources do not mark it as known exploited. The current feed maps bookstackapp/bookstack (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps bookstackapp/bookstack (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| bookstackapp/bookstackgeneric | >=0 <26.05.4 | 26.05.4 |
Published upstream
Aug 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 29, 2026
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.
Quoted source text, attributed separately from HOL analysis.