index.md

---

title: "CSP: worker-src"
slug: Web/HTTP/Headers/Content-Security-Policy/worker-src
browser-compat: http.headers.Content-Security-Policy.worker-src

---

{{HTTPSidebar}}

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

CSP version	3
Directive type	{{Glossary("Fetch directive")}}
Fallback	If this directive is absent, the user agent will first look for the {{CSP("child-src")}} directive, then the {{CSP("script-src")}} directive, then finally for the {{CSP("default-src")}} directive, when governing worker execution.

Syntax

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

Content-Security-Policy: worker-src <source>;
Content-Security-Policy: worker-src <source> <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 {{Glossary("fetch directive", "fetch directives")}} (and a number of other directives).

Examples

Violation cases

Given this CSP header:

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

{{domxref("Worker")}}, {{domxref("SharedWorker")}}, {{domxref("ServiceWorker")}} are blocked and won't load:

<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

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{HTTPHeader("Content-Security-Policy")}}

• CSP for Web Workers

• {{domxref("Worker")}}, {{domxref("SharedWorker")}}, {{domxref("ServiceWorker")}}