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Glossary Term

Email Header Injection

Manipulating email-sending forms to add malicious headers, send spam, or redirect messages.

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Email Header Injection

1-minute read

What it is

Email Header Injection happens when attackers manipulate email messages by inserting hidden commands into form fields.

Why it matters

It can be used to send spam, fake emails, or redirect messages without being noticed.

How to reduce risk

  • Properly clean all email form inputs
  • Block special characters in email fields
  • Monitor unusual email sending patterns

External resources

  • https://owasp.org/www-community/attacks/Email_Header_Injection
  • https://portswigger.net/web-security/email-injection