Attackers use newline characters ( \r\n or %0A%0D ) to "break out" of the intended field and insert their own SMTP headers.
Attackers can add Bcc: victim@example.com to turn your contact form into a spam relay. php email form validation - v3.1 exploit
You're referring to a well-known vulnerability in PHP's email form validation. Attackers use newline characters ( \r\n or %0A%0D
When storing email addresses in databases, always use prepared statements or parameterized queries to prevent SQL injection. Never concatenate email values directly into SQL queries. When storing email addresses in databases, always use
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$clean_email = htmlspecialchars($email, ENT_QUOTES, 'UTF-8'); $stmt = $pdo->prepare("INSERT INTO users (email) VALUES (?)"); $stmt->execute([$clean_email]);