How to secure file uploads?

Updated May 6, 2026

Short answer

Validate, sanitize, and restrict file uploads.

Deep explanation

Check MIME type, file size, rename files, and store outside web root.

Real-world example

Preventing malicious PHP uploads.

Common mistakes

  • Trusting file extensions.

Follow-up questions

  • What is content sniffing?
  • How to store uploads safely?

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