What Is Host Header Injection Attack?

In this article, learn about host headers, host header injection attacks, host header injection attack impact, and prevention methods of this injection attack.

Many use WordPress for various reasons, but the common thing among all WordPress users is security. There are many vulnerabilities in a website that allow a hacker to attack and mess with your website. One such vulnerability is the host header injection attack. 

Few well-known injection attacks are SQL injection attacks, Code injection attacks, XPath injection attacks, XSS, and more. These attacks work based on the same principle but in different ways; hackers use injection attacks to insert malicious code into the target website. Doing this results in changing the course of action of the website’s program, which, of course, is the hacker’s intent.

Injection attacks can cause a lot of damage to your website if you do not take care of the website’s vulnerabilities. Website security deserves our utmost attention, and we should do our best for our website protection. Keep reading this article to learn about host header injection attacks and the methods to prevent the attack on your website. 

what is host header injection attack

What Is A Host Header?

We all know that a single web server can host various websites. So how does this server distribute the incoming requests to the specified websites? Yeah, you got the correct answer; host headers.

The websites using the same web server while sharing the same IP address are known as ” Virtual hosts.”

The HTTP Host header specifies which website should receive the incoming data. It looks like Host headers are doing a great job; then, how will a hacker use host headers to exploit your website? Let’s see.

Host Header Injection Attack

The attack that works by inserting malicious code to host headers is a Host header injection attack. When a website uses the value of the host headers in an unsafe way, it acts as a vulnerability for a hacker to exploit. This attack can lead hackers to change the server-side behavior. This attack mainly happens during password reset.

A hacker requests to reset a password while controlling the host header, the server sends an email regarding the reset request containing a link. When the user clicks on that link, the attacker obtains the reset link and will change the password. Thereby, the hacker gains access to your website. A hacker can use password reset poisoning and also web cache poisoning using the host header injection attack.

Web cache poisoning will result in showing poisoned/ tampered content to traffic when requested for it. It will immensely impact your website’s reputation, and you will be able to do nothing about it. No one would wish for that helplessness. All you have to do is avoid host header vulnerabilities as soon as possible.

What Is The Impact Of A Host Header Injection Attack?

Every attack will have an aftermath that will prove to be a headache to you. If you fail to protect your website from a Host header injection attack then, the following are the possible outcomes:

  • Redirection from your website to another can happen,
  • Financial loss may occur,
  • It can lead to a hacker exploiting other vulnerabilities like XSS vulnerabilities, SQL injection vulnerabilities,
  • Theft of login credentials,
  • hackers can gain access to internal hosts,
  • Web cache poisoning.

How To Prevent Host Header Injection Attacks?

 It is necessary to avoid all security mistakes and take needed measures to prevent attacks from happening. So, listed below are the ways to block the host header injection attacks:

1. Validation

Validation is a common practice when it comes to preventing injection attacks. We must validate host headers by checking them with the safe domains and rejecting requests from unknown/unsafe hosts.

2. Avoid Default Host Headers

Other default headers will be helpful to hackers. So we must disable support to these host headers. One example of the Host override header is X-Forwarded-Host.

3. Avoid Internal Only Virtual Hosts

When using virtual hosts, avoid internal-only websites because it can lead hackers to access internal domains.

4. Say No To Host headers

Avoid using host headers unless you have to use them. If there aren’t any host headers, a hacker cannot use its vulnerabilities. It’s that simple.

Like host header injection attacks, hackers use various methods to attack a website. Hence, to protect a website, we must detect the vulnerabilities by using security scanners like Scan My WP and protect websites using security plugins like the Hide My WP. Hide My WP is an advanced WordPress security plugin that helps users protect their WordPress from various attacks. This plugin is helpful in the following ways:

hide my wp security plugin
  • It can hide from the world that you are a WordPress user,
  • It will help you hide the login page of your website to prevent brute-force attacks,
  • It will hide your WordPress from theme and plugin detectors,
  • It will let you change anything in your source code,
  • It allows changing permalinks,
  • It can hide/ rename WP-admin,
  • It has a firewall that can block dangerous attacks like SQL, XSS, CSRF, read arbitrary files, and brute force attacks
  • It has a “trust network” with which we can block attacks from known hackers and bots,
  • It can allow and block users from specific countries of your choice,
  • It can disable direct access to directory listings and PHP files.

Hide My WP targets many vulnerabilities at once, making it a suitable choice for your website security.


  • WordPress security is of great importance. Hence, we must always look for security issues and fix them immediately. Hackers often use injection attacks to trespass on a website, and a Host header injection attack is one of them.
  • Host headers help web servers direct requests to specified websites.
  • Hackers use host header injection attacks to manipulate server-side behavior.
  • If a hacker gets successful with the host header injection attack, it will hugely impact your website.
  • Hence, we must avoid host header injection vulnerabilities at all costs.
  • You can prevent this injection attack by validating host headers, avoiding host override headers, and using internal-only virtual hosts. Last but not least, avoid using host headers themselves.
  • We can use many security plugins that help protect websites from different kinds of attacks. This step will provide absolute security.

Also read: What Is An Email Header Injection Attack?