What are common pitfalls when validating user input in PHP?

One common pitfall when validating user input in PHP is not properly sanitizing the input, which can lead to security vulnerabilities such as SQL injection or cross-site scripting attacks. To solve this issue, always sanitize user input by using functions like htmlspecialchars() or mysqli_real_escape_string() before using it in your application. 

// Example of sanitizing user input using htmlspecialchars()
$user_input = "<script>alert('XSS attack');</script>";
$sanitized_input = htmlspecialchars($user_input, ENT_QUOTES, 'UTF-8');
echo $sanitized_input;

Keywords

XSS SQL injection filter_var htmlspecialchars validation errors

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