HTTP Host Header Attacks Template

Executive Summary:

This report addresses a critical security vulnerability known as HTTP Host Header Attacks within our application. HTTP Host Header Attacks occur when attackers manipulate the Host header in HTTP requests to bypass security controls, poison caches, or perform various types of attacks, including server-side request forgery (SSRF) and cache poisoning. This report aims to detail the vulnerability, its potential impact on our systems and users, and actionable recommendations for mitigation.

Description of the Vulnerability:

HTTP Host Header Attacks exploit weaknesses in the handling of the Host header by web servers or applications. Attackers can manipulate the Host header to perform attacks such as server-side request forgery (SSRF), cache poisoning, or bypassing access controls. By crafting malicious requests with manipulated Host headers, attackers can trick the server into processing requests intended for other hosts or executing unauthorized actions.


The impact of HTTP Host Header Attacks can be severe, leading to various security risks including unauthorized access to internal resources, data exposure, or compromise of sensitive information. Attackers can exploit these vulnerabilities to bypass security controls, manipulate server behavior, or access sensitive data, potentially leading to financial loss, reputational damage, or legal consequences.


The likelihood of exploitation depends on various factors including the visibility of the Host header, the effectiveness of input validation, and the attacker's knowledge and motivation. However, given the prevalence of HTTP Host Header Attacks in web applications and the potential impact on system security and user privacy, the risk associated with this vulnerability is significant if not properly mitigated.

Steps to Reproduce:

  1. Craft malicious HTTP requests with manipulated Host headers targeting the application's server.
  2. Analyze the application's response to the malicious requests and observe if the server processes the requests as intended by the attacker.
  3. Determine if the attacker can access unauthorized resources, perform unauthorized actions, or manipulate server behavior using the manipulated Host header.
  4. Analyze the impact of successful exploitation, including potential data exposure, server compromise, or unauthorized access to sensitive information.

Recommendations for Developers:

  1. Validate Host Header: Implement strict validation of the Host header to ensure that it corresponds to expected values and does not contain unexpected characters or patterns.
  2. Use Whitelisting: Use whitelisting techniques to restrict the allowed values of the Host header to known and trusted hosts, preventing attackers from manipulating the header to access unauthorized resources.


Addressing HTTP Host Header Attacks is critical to protecting against server-side request forgery (SSRF), cache poisoning, and unauthorized access within our application. By implementing strict validation of the Host header and using whitelisting techniques, we can mitigate the risks associated with HTTP Host Header Attacks and enhance the overall security posture of our systems.