CVE-2002-1771 in FormMail
Summary
by MITRE
Matt Wright FormMail 1.9 and earlier allows remote attackers to send spam or anonymous e-mail by injecting a newline character followed by CC:, BCC:, or additional TO: fields in the email and realname CGI variables.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 09/01/2025
The vulnerability described in CVE-2002-1771 affects Matt Wright FormMail version 1.9 and earlier, representing a classic example of input validation failure that enables malicious actors to manipulate email transmission parameters. This issue resides within the CGI script's handling of user-supplied data in email and realname variables, creating a path for unauthorized email injection attacks that can be leveraged for spam distribution or anonymous messaging.
The technical flaw manifests through improper sanitization of input fields where attackers can insert newline characters followed by email headers such as CC:, BCC:, or additional TO: fields. This exploitation technique exploits the fundamental weakness in how the application processes user input without adequate validation or encoding of special characters. When the CGI script processes these malicious inputs, it concatenates the injected headers directly into the email message structure, effectively bypassing normal email sending restrictions and allowing attackers to manipulate recipient lists and email routing.
The operational impact of this vulnerability extends beyond simple spam distribution to encompass potential privacy violations and abuse of the mail system. Attackers can use this vulnerability to send emails to unintended recipients through BCC injection, making it difficult to trace the actual sender. The vulnerability also enables mass email distribution by allowing attackers to add multiple recipients to the CC or BCC fields, potentially overwhelming target email systems or distributing unsolicited messages at scale. This represents a significant concern for organizations relying on FormMail for legitimate email processing, as it transforms a simple contact form into a vector for malicious email activity.
Security professionals should recognize this vulnerability as a variant of CWE-174, which describes weakness in input validation where programs fail to properly validate or sanitize user input before using it in security-critical operations. The attack pattern aligns with ATT&CK technique T1192, which covers "Spoofing" through email header manipulation, and T1193, which involves "Spearphishing Attachment" through email injection techniques. Organizations should implement immediate mitigations including input validation of all user-supplied email fields, proper encoding of special characters, and regular updates to deprecated software components. The vulnerability demonstrates the critical importance of proper input sanitization in web applications and serves as a reminder of the long-lasting security implications of legacy software components that remain in production environments without proper security updates.