CSP: child-src

The HTTP Content-Security-Policy (CSP) child-src directive defines the valid sources for web workers and nested browsing contexts loaded using elements such as <frame> and <iframe>. For workers, non-compliant requests are treated as fatal network errors by the user agent.

CSP version 2
Directive type Fetch directive
default-src fallback Yes. If this directive is absent, the user agent will look for the default-src directive.


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

Content-Security-Policy: child-src <source>;
Content-Security-Policy: child-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: child-src https://example.com/

This <iframe> and worker are blocked and won't load:

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

  const blockedWorker = new Worker("data:application/javascript,…");


Content Security Policy Level 3
# directive-child-src

Browser compatibility

BCD tables only load in the browser

See also