File Type Validation

Definitions

1. The process of confirming that an uploaded or processed file is really the type it claims to be, using MIME checks, magic bytes, parsing, or allowlists rather than trusting the extension alone. Weak file type validation often leads to upload abuse, parser exploitation, or hidden executable content.

   In plain English: Making sure a file is truly the kind of file it claims to be.

   Example: "The bug existed because the app only checked the extension and skipped real file type validation."

Related Terms

• Boundary Check
• AppSec
• Code Audit
• Code Vulnerability
• Health Check Security
• Macro Security
• MIME Type Attack
• REST API Security