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

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.)

Syntax

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:
    • 'unsafe-hashes'
    • 'unsafe-inline'
    • 'report-sample'

script-src-attr can be used in conjunction with script-src, and will override that directive for checks on inline handlers:

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

Examples

Violation case

Given this CSP header:

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

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

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

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

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

Specifications

Browser compatibility

See also

• Content-Security-Policy
• script
• script-src
• script-src-elem