ctive is absent, the user agent will look for the [ ` child-src ` ](/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/child-src) directive (which falls back to the [ ` default-src ` ](/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/default-src) directive).   
  
##  Syntax

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

http

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

###  Sources

` <source> ` can be any one of the values listed in [ CSP Source Values ](/en-
US/docs/Web/HTTP/Headers/Content-Security-Policy/Sources#sources) .

Note that this same set of values can be used in all [ fetch directives ](/en-
US/docs/Glossary/Fetch_directive) (and a [ number of other directives ](/en-
US/docs/Web/HTTP/Headers/Content-Security-Policy/Sources#relevant_directives)
).

##  Examples

###  Violation cases

Given this CSP header:

http

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

The following [ ` <iframe> ` ](/en-US/docs/Web/HTML/Element/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  ](https://w3c.github.io/webappsec-csp/#directive-
frame-src)  
  
##  Browser compatibility

BCD tables only load in the browser  with JavaScript enabled. Enable
JavaScript to view data.

##  See also

  * [ ` Content-Security-Policy ` ](/en-US/docs/Web/HTTP/Headers/Content-Security-Policy)
  * [ ` <frame> ` ](/en-US/docs/Web/HTML/Element/frame) and [ ` <iframe> ` ](/en-US/docs/Web/HTML/Element/iframe)
  * [ ` frame-ancestors ` ](/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/frame-ancestors)

##  Help improve MDN

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