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email-header-injection

Test SMTP email systems for header injection and spoofing vulnerabilities.

Updated Jun 11, 2026
Search Tags:#authentication bypass#email header injection#SMTP security#email vulnerability#phishing attack
One-click install
npx skills add https://github.com/utsavthakur/agenticskills --skill email-header-injection-utsavthakur
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: email-header-injection
Source: https://github.com/utsavthakur/agenticskills/tree/main/email-header-injection
Command: npx skills add https://github.com/utsavthakur/agenticskills --skill email-header-injection-utsavthakur

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires smtplib, email, pytz, and includes scripts (resource) and references (resource) components.

What problem does it solve?

This Skill solves the problem of email header injection and spoofing, helping to test contact forms, email APIs, password reset flows, and other features that construct SMTP messages with user-controlled fields.

Core Features & Use Cases

  • Email Header Injection: Covers CRLF injection, SPF/DKIM/DMARC bypass, and phishing amplification.
  • Authentication Bypass: Detects and mitigates vulnerabilities in email authentication mechanisms.
  • Use Case: It can be used by security professionals to identify and test vulnerabilities in email systems, ensuring that they are secure against header injection and spoofing attacks.

Quick Start

Execute the script 'test-injection.py' within the email-header-injection skill directory to test for email header injection vulnerabilities.

Frequently Asked Questions about email-header-injection

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I test for email header injection vulnerabilities in contact forms?▼

To test for email header injection in contact forms, execute the test-injection.py script within the skill directory to identify CRLF injection and header manipulation vulnerabilities in SMTP-based systems.

What is email header injection and how does it bypass SPF, DKIM, and DMARC?▼

Email header injection is a technique exploiting CRLF sequences to manipulate SMTP headers, enabling SPF, DKIM, and DMARC bypass for spoofing and phishing amplification attacks.

Can I use Python smtplib to test SMTP spoofing and authentication bypass?▼

Yes, this Skill uses Python smtplib and the email library to test SMTP spoofing and authentication bypass, validating email system security against header manipulation vulnerabilities.

What's the best way to validate email system security against phishing amplification?▼

The best way to validate email system security is using this Skill to examine header manipulation and test authentication bypass in password reset flows and email APIs.

Why does CRLF injection in email APIs allow spoofing of SMTP messages?▼

CRLF injection in email APIs allows spoofing because user-controlled fields inject carriage return and line feed characters, altering SMTP message headers and bypassing authentication mechanisms.

Do I need to install pytz to test email header injection vulnerabilities?▼

Yes, pytz is a required dependency alongside smtplib and email libraries to run the test-injection.py script and validate authentication bypass vulnerabilities in SMTP systems.

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