Content-Security-Policy: script-src-attr directive
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since December 2022.
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.
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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:
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
| Specification |
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| Content Security Policy Level 3 # directive-script-src-attr |
Browser compatibility
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script-src-attr
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Legend
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- Full support
- Full support