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Content-Security-Policy: frame-src directive

files/en-us/web/http/reference/headers/content-security-policy/frame-src/index.md

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The HTTP {{HTTPHeader("Content-Security-Policy")}} (CSP) frame-src directive specifies valid sources for nested browsing contexts loading using elements such as {{HTMLElement("frame")}} and {{HTMLElement("iframe")}}.

[!NOTE] frame-src allows you to specify where iframes in a page may be loaded from. This differs from frame-ancestors, which allows you to specify what parent source may embed a page.

<table class="properties"> <tbody> <tr> <th scope="row">CSP version</th> <td>1</td> </tr> <tr> <th scope="row">Directive type</th> <td>{{Glossary("Fetch directive")}}</td> </tr> <tr> <th scope="row">Fallback</th> <td> If this directive is absent, the user agent will look for the {{CSP("child-src")}} directive (which falls back to the {{CSP("default-src")}} directive). </td> </tr> </tbody> </table>

Syntax

http
Content-Security-Policy: frame-src 'none';
Content-Security-Policy: frame-src <source-expression-list>;

This directive may have one of the following values:

  • 'none'
    • : No resources of this type may be loaded. The single quotes are mandatory.
  • <source-expression-list>
    • : A space-separated list of source expression values. Resources of this type may be loaded if they match any of the given source expressions. For this directive, the following source expression values are applicable:

Examples

Violation cases

Given this CSP header:

http
Content-Security-Policy: frame-src https://example.com/

The following {{HTMLElement("iframe")}} is blocked and won't load:

html
<iframe src="https://not-example.com/"></iframe>

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

  • {{HTTPHeader("Content-Security-Policy")}}
  • {{HTMLElement("frame")}} and {{HTMLElement("iframe")}}
  • {{CSP("frame-ancestors")}}