What are the potential pitfalls when using the enctype="multipart/form-data" attribute in a form for file uploads?

Potential pitfalls when using enctype="multipart/form-data" for file uploads include increased server load due to larger file sizes, potential security vulnerabilities if not properly sanitized, and potential issues with file naming conflicts. To solve these issues, it is important to validate and sanitize user input, limit file upload sizes, and generate unique file names to prevent conflicts. 

// Example PHP code snippet to validate file size and generate unique file names for uploaded files
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $uploadDir = 'uploads/';
    $uploadFile = $uploadDir . uniqid() . '_' . basename($_FILES['file']['name']);

    if ($_FILES['file']['size'] > 5000000) {
        echo 'File size is too large. Please upload a file smaller than 5MB.';
    } else {
        if (move_uploaded_file($_FILES['file']['tmp_name'], $uploadFile)) {
            echo 'File is valid, and was successfully uploaded.';
        } else {
            echo 'Upload failed. Please try again.';
        }
    }
}

Keywords

PHP enctype multipart/form-data file uploads potential pitfalls

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