index.md

---

title: "CSP: frame-src"
slug: Web/HTTP/Headers/Content-Security-Policy/frame-src
browser-compat: http.headers.Content-Security-Policy.frame-src

---

{{HTTPSidebar}}

The HTTP {{HTTPHeader("Content-Security-Policy")}} (CSP) frame-src directive specifies valid sources for nested browsing contexts loading using elements such as {{HTMLElement("frame")}} and {{HTMLElement("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	{{Glossary("Fetch directive")}}
Fallback	If this directive is absent, the user agent will look for the {{CSP("child-src")}} directive (which falls back to the {{CSP("default-src")}} directive).

Syntax

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>;

Sources

<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 {{Glossary("fetch directive", "fetch directives")}} (and a number of other directives).

Examples

Violation cases

Given this CSP header:

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

The following {{HTMLElement("iframe")}} is blocked and won't load:

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

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{HTTPHeader("Content-Security-Policy")}}

• {{HTMLElement("frame")}} and {{HTMLElement("iframe")}}

• {{CSP("frame-ancestors")}}