CSP: script-src-attr

The HTTP 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 <script> elements and XSLT stylesheets. (Valid sources can be specified for all JavaScript script sources using script-src, or just for <script> elements using script-src-elem.)

CSP version 3
Directive type Fetch directive
default-src fallback Yes. If this directive is absent, the user agent will look for the script-src directive, and if both of them are absent, fallback to default-src directive.

Syntax

One or more sources can be allowed for the script-src-attr policy:

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

script-src-attr can be used in conjunction with 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>;

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 fetch directives (and a number of other directives).

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()"></button>

Note that generally you should replace inline event handlers with addEventListener calls:

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

Specifications

Specification
Content Security Policy Level 3
# directive-script-src-attr

Browser compatibility

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See also