CVE-2025-59419

Name of the Vulnerable Software and Affected Versions Netty versions prior to 4.1.128.Final and 4.2.7.Final

Description Netty contains an SMTP command injection vulnerability due to insufficient input validation for Carriage Return (r) and Line Feed ( ) characters in user-supplied parameters. The vulnerability exists in io.netty.handler.codec.smtp.DefaultSmtpRequest, where parameters are directly concatenated into the SMTP command string without sanitization. When methods such as SmtpRequests.rcpt(recipient) are called with a malicious string containing CRLF sequences, attackers can inject arbitrary SMTP commands. Because the injected commands are sent from the server’s trusted IP address, resulting emails will likely pass SPF and DKIM authentication checks, allowing attackers to forge emails from the trusted server. This could lead to economic manipulation, disinformation, and sophisticated phishing attacks. A proof-of-concept (PoC) is available demonstrating the vulnerability against a local SMTP server.

Recommendations Upgrade to Netty version 4.1.128.Final or 4.2.7.Final or later.