CSP: worker-src

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since August 2016.

The HTTP Content-Security-Policy (CSP) worker-src directive specifies valid sources for Worker, SharedWorker, or ServiceWorker scripts.

CSP version 3
Directive type Fetch directive
Fallback

If this directive is absent, the user agent will first look for the child-src directive, then the script-src directive, then finally for the default-src directive, when governing worker execution.

Syntax

http
Content-Security-Policy: worker-src 'none';
Content-Security-Policy: worker-src <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:

Examples

Violation cases

Given this CSP header:

http
Content-Security-Policy: worker-src https://example.com/

Worker, SharedWorker, ServiceWorker are blocked and won't load:

html
<script>
  let blockedWorker = new Worker("data:application/javascript,…");
  blockedWorker = new SharedWorker("https://not-example.com/");
  navigator.serviceWorker.register("https://not-example.com/sw.js");
</script>

Specifications

Specification
Content Security Policy Level 3
# directive-worker-src

Browser compatibility

BCD tables only load in the browser

See also