In sourcecodetester Engineers Online Portal as of 10-21-21, an attacker can manipulate the Host header as seen by the web application and cause the application to behave in unexpected ways. Very often multiple websites are hosted on the same IP address. This is where the Host Header comes in. This header specifies which website should process the HTTP request. The web server uses the value of this header to dispatch the request to the specified website. Each website hosted on the same IP address is called a virtual host. And It's possible to send requests with arbitrary Host Headers to the first virtual host.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-43437
• https://medium.com/@mayhem7999/cve-2021-43437-5c5e3b977e84
• https://portswigger.net/web-security/host-header