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Content-Security-Policy: script-src-attr directive

files/en-us/web/http/reference/headers/content-security-policy/script-src-attr/index.md

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The HTTP {{HTTPHeader("Content-Security-Policy")}} (CSP) script-src-attr directive specifies valid sources for JavaScript inline event handlers.

This directive only specifies valid sources for inline script event handlers like onclick. It does not apply to other JavaScript sources that can trigger script execution, such as URLs loaded directly into {{HTMLElement("script")}} elements and XSLT stylesheets. (Valid sources can be specified for all JavaScript script sources using {{CSP("script-src")}}, or just for <script> elements using {{CSP("script-src-elem")}}.)

<table class="properties"> <tbody> <tr> <th scope="row">CSP version</th> <td>3</td> </tr> <tr> <th scope="row">Directive type</th> <td>{{Glossary("Fetch directive")}}</td> </tr> <tr> <th scope="row">{{CSP("default-src")}} fallback</th> <td> Yes. If this directive is absent, the user agent will look for the {{CSP("script-src")}} directive, and if both of them are absent, fallback to <code>default-src</code> directive. </td> </tr> </tbody> </table>

Syntax

http
Content-Security-Policy: script-src-attr 'none';
Content-Security-Policy: script-src-attr <source-expression-list>;

This directive may have one of the following values:

  • 'none'
    • : No resources of this type may be loaded. The single quotes are mandatory.
  • <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:

script-src-attr can be used in conjunction with {{CSP("script-src")}}, and will override that directive for checks on inline handlers:

http
Content-Security-Policy: script-src <source>;
Content-Security-Policy: script-src-attr <source>;

Examples

Violation case

Given this CSP header:

http
Content-Security-Policy: script-src-attr 'none'

…the following inline event handler is blocked and won't be loaded or executed:

html
<button id="btn" onclick="doSomething()">Click me</button>

Note that generally you should replace inline event handlers with {{domxref("EventTarget.addEventListener", "addEventListener")}} calls:

js
document.getElementById("btn").addEventListener("click", doSomething);

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

  • {{HTTPHeader("Content-Security-Policy")}}
  • {{HTMLElement("script")}}
  • {{CSP("script-src")}}
  • {{CSP("script-src-elem")}}