What are the potential pitfalls of not properly escaping characters in PHP form tags?

Not properly escaping characters in PHP form tags can leave your application vulnerable to cross-site scripting (XSS) attacks, where malicious scripts can be injected into the form fields and executed on the client's browser. To prevent this, you should always use the htmlspecialchars() function to escape any user input before displaying it on the page. 

<form action="submit.php" method="post">
    <input type="text" name="username" value="<?php echo htmlspecialchars($_POST['username']); ?>">
    <input type="submit" value="Submit">
</form>

Keywords

SQL injection XSS attacks htmlentities htmlspecialchars security vulnerabilities

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