https://nalar.dev/tags/input-validation/ Recent content in Input Validation on Nalar Hugo en-us Thu, 03 Sep 2026 00:00:00 +0700 https://nalar.dev/secure-file-upload-handling/ Thu, 03 Sep 2026 00:00:00 +0700 https://nalar.dev/secure-file-upload-handling/ <p>File uploads cross a security boundary. A file supplied by a user may have a misleading name, unexpected content, excessive size, malicious active content, or a structure designed to exploit the software that processes it.</p> <p>Secure upload handling therefore requires more than checking a filename extension. Treat every uploaded file as untrusted until the application has validated, stored, processed, and served it according to an explicit policy.</p> <h2 id="start-with-a-narrow-upload-policy">Start with a narrow upload policy</h2> <p>Define what the feature actually needs to accept. An avatar service may need only a small set of image formats, while a document workflow may need PDF files and nothing else.</p>