Php Email Form Validation - V3.1 Exploit |top|

Attackers can add Bcc: victim@example.com to turn your contact form into a spam relay.

No specialized tools are required; a simple browser or curl command suffices. php email form validation - v3.1 exploit

The vulnerability lies in how email headers are structured. Headers are separated by a Carriage Return and Line Feed (CRLF), represented in PHP as \r\n . In a secure environment, the code ensures that the user's input does not contain these characters. However, legacy scripts often omit this check, allowing an attacker to terminate the intended header line and inject entirely new ones. Attackers can add Bcc: victim@example