SMTP Header Injection

Description

The application is vulnerable to SMTP header injection. This occurs when user input is placed in a header line without removing or replacing new line characters (CR/LF), allowing an attacker to inject malicious headers.

Examples

Insecure Code

MimeMessage message = new MimeMessage();
message.setSubject(userInput);

Secure Code

MimeMessage message = new MimeMessage();
message.setSubject(SanitizeInput(userInput));

Remediation

Use a safe wrapper such as Apache Common Email and Simple Java Mail which filter special characters that can lead to header injection. Ensure that user input is properly sanitized before being used in SMTP headers.

Rule Details

Field	Value
ID	CODE-0066
Category	Injection
Severity	HIGH
CWE	CWE-77
Confidence	HIGH
Impact	HIGH
Likelihood	MEDIUM
Exploitability	EASY
Tags	header injection, SMTP
OWASP	N/A

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