Headers: CSP.fenced-frame-src

Content-Security-Policy: fenced-frame-src directive

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Learn more
See full compatibility

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The HTTP Content-Security-Policy (CSP) fenced-frame-src directive specifies valid sources for nested browsing contexts loaded into <fencedframe> elements.

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

Syntax

Content-Security-Policy: fenced-frame-src <source-expression-list>;

<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:

The <host-source> value "https:"
The <scheme-source> value "https:"
The string "*"

Examples

Violation cases

Given this CSP header:

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

The following sources will not load in a fenced frame:

https://not-example.com/ (domain doesn't match)
https://example.org/ (TLD doesn't match)

Specifications

Specification
Fenced Frame> # new-csp-directive>

Browser compatibility

	Desktop					Mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	WebView on iOS
`fenced-frame-src`	126	126	No	112	No	126	No	83	No	28.0	126	No