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.

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

http
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:

Examples

Violation cases

Given this CSP header:

http
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
Experimental
Chrome – Full support
Chrome 126 (Release date: 2024-06-11)
footnote Full support
Edge – Full support
Edge 126 (Release date: 2024-06-13)
footnote Full support
Firefox – No support
Firefox
footnote No support
Opera – Full support
Opera 112 (Release date: 2024-07-11)
footnote Full support
Safari – No support
Safari
footnote No support
Chrome Android – Full support
Chrome Android 126 (Release date: 2024-06-11)
footnote Full support
Firefox for Android – No support
Firefox for Android
footnote No support
Opera Android – Full support
Opera Android 83 (Release date: 2024-06-25)
footnote Full support
Safari on iOS – No support
Safari on iOS
footnote No support
Samsung Internet – Full support
Samsung Internet 28 (Release date: 2025-04-02)
footnote Full support
WebView Android – Full support
WebView Android 126 (Release date: 2024-06-11)
footnote Full support
WebView on iOS – No support
WebView on iOS
footnote No support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support
Experimental. Expect behavior to change in the future.

See also