Clickjacking prevention

The Content Security Policy frame-ancestors directive and the X-Frame-Options header provide control over how your site may be embedded within an <iframe> on another site. These features help prevent clickjacking.


Clickjacking is an attack whereby malicious sites trick users into clicking links or UI elements by making them appear like a trusted site the user is familiar with. This is usually done by embedding part or all of the trusted site into the malicious site via an <iframe>. A button, link, or other UI feature is then positioned on top of that content to make the user think they are interacting with their trusted site, when in fact they are interacting with the malicious site.


Use the HTTP headers as required:

  • Content-Security-Policy: frame-ancestors is preferred as it provides more granular control over site embedding. It is however not supported in IE11 and earlier, pre-Chromium versions of Edge, Safari 9.1 (desktop), and Safari 9.2 (iOS).
  • X-Frame-Options is less granular, but it is supported in the older browser set listed above.

The recommendation is to use both unless you know you don't need support for the older browser set.

You should deny all attempts to embed your site unless you really need to. When embedding is required, provide the minimum embedding allowance necessary. Sites that require the ability to be embedded in an <iframe> must use JavaScript defenses and a robust Content-Security-Policy to prevent clickjacking from malicious origins. Window.confirm() can be used as part of your JavaScript defenses to inform the user of the action they are about to perform: See window.confirm() Protection.

The equivalent options for each setting are as follows:

CSP value X-Frame-Options value Description
frame-ancestors 'none' DENY Deny all embedding attempts.
frame-ancestors 'self' SAMEORIGIN Allow only same-origin embedding attempts.
frame-ancestors ALLOWFROM Allow embedding attempts from the specified domain.

Note: The X-Frame-Options: ALLOWFROM syntax is deprecated, and most browsers ignore it. You are recommend to set DENY in such cases instead, and/or rely on the CSP equivalent.

Note: Setting cookies with the SameSite directive is also useful in clickjacking cases that rely on the user being authenticated.


Block the site from being embedded by using X-Frame-Options and CSP:

Content-Security-Policy: frame-ancestors 'none'
X-Frame-Options: DENY

Allow the site to be embedded only on same-origin pages:

Content-Security-Policy: frame-ancestors 'self'
X-Frame-Options: SAMEORIGIN

Only allow to embed the site:

Content-Security-Policy: frame-ancestors
# Block embedding in browsers that don't support CSP2
X-Frame-Options: DENY

See also