CSP: frame-src

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).


One or more sources can be allowed for the frame-src policy:

Content-Security-Policy: frame-src <source>;
Content-Security-Policy: frame-src <source> <source>;


<source> can be any one of the values listed in CSP Source Values.

Note that this same set of values can be used in all fetch directives (and a number of other directives).


Violation cases

Given this CSP header:

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

The following <iframe> is blocked and won't load:

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


Content Security Policy Level 3
# directive-frame-src

Browser compatibility

BCD tables only load in the browser

See also