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# Security

This document explains some of AngularJS's security features and best practices that you should keep in mind as you build your application.

## Expression Sandboxing

AngularJS's expressions are sandboxed not for security reasons, but instead to maintain a proper separation of application responsibilities. For example, access to `window` is disallowed because it makes it easy to introduce brittle global state into your application.

However, this sandbox is not intended to stop attackers who can edit the template before it's processed by Angular. It may be possible to run arbitrary JavaScript inside double-curly bindings if an attacker can modify them.

But if an attacker can change arbitrary HTML templates, there's nothing stopping them from doing:

    <script>somethingEvil();</script>

It's better to design your application in such a way that users cannot change client-side templates. For instance:

- Do not mix client and server templates
- Do not use user input to generate templates dynamically
- Do not run user input through `$scope.$eval`
- Consider using CSP (but don't rely only on CSP)

## Mixing client-side and server-side templates

In general, we recommend against this because it can create unintended XSS vectors.

However, it's ok to mix server-side templating in the bootstrap template (`index.html`) as long as user input cannot be used on the server to output html that would then be processed by Angular in a way that would cause allow for arbitrary code execution.

For instance, you can use server-side templating to dynamically generate CSS, URLs, etc, but not for generating templates that are bootstrapped/compiled by Angular.

## Reporting a security issue

Email us at security@angularjs.org to report any potential security issues in AngularJS.

Please keep in mind the above points about Angular's expression language.

## See also

- Content Security Policy
- Strict Contextual Escaping
- $sanitize