CSP: frame-src

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since August 2016.

The HTTP Content-Security-Policy (CSP) frame-src directive specifies valid sources for nested browsing contexts loading using elements such as <frame> and <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.

CSP version 1
Directive type Fetch directive
Fallback If this directive is absent, the user agent will look for the child-src directive (which falls back to the default-src directive).

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 <iframe> is blocked and won't load:

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

Specifications

Specification
Content Security Policy Level 3
# directive-frame-src

Browser compatibility

BCD tables only load in the browser

See also