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 Chrome 59 and higher skips the Edge 17 skips the |
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 one of the following:
- <host-source>
- Internet hosts by name or IP address, as well as an optional URL scheme and/or port number. The site's address may include an optional leading wildcard (the asterisk character,
'*'
), and you may use a wildcard (again,'*'
) as the port number, indicating that all legal ports are valid for the source.
Examples:http://*.example.com
: Matches all attempts to load from any subdomain of example.com using thehttp:
URL scheme.mail.example.com:443
: Matches all attempts to access port 443 on mail.example.com.https://store.example.com
: Matches all attempts to access store.example.com usinghttps:
.*.example.com
: Matches all attempts to load from any subdomain of example.com using the current protocol.
- <scheme-source>
- A schema such as 'http:' or 'https:'. The colon is required, single quotes shouldn't be used. You can also specify data schemas (not recommended).
data:
Allowsdata:
URIs to be used as a content source. This is insecure; an attacker can also inject arbitrary data: URIs. Use this sparingly and definitely not for scripts.mediastream:
Allowsmediastream:
URIs to be used as a content source.blob:
Allowsblob:
URIs to be used as a content source.filesystem:
Allowsfilesystem:
URIs to be used as a content source.
'self'
- Refers to the origin from which the protected document is being served, including the same URL scheme and port number. You must include the single quotes. Some browsers specifically exclude
blob
andfilesystem
from source directives. Sites needing to allow these content types can specify them using the Data attribute. 'unsafe-eval'
- Allows the use of
eval()
and similar methods for creating code from strings. You must include the single quotes. 'unsafe-hashes'
- Allows to enable specific inline event handlers. If you only need to allow inline event handlers and not inline
<script>
elements orjavascript:
URLs, this is a safer method compared to using theunsafe-inline
expression. 'unsafe-inline'
- Allows the use of inline resources, such as inline
<script>
elements,javascript:
URLs, inline event handlers, and inline<style>
elements. You must include the single quotes. 'none'
- Refers to the empty set; that is, no URLs match. The single quotes are required.
- 'nonce-<base64-value>'
- A whitelist for specific inline scripts using a cryptographic nonce (number used once). The server must generate a unique nonce value each time it transmits a policy. It is critical to provide an unguessable nonce, as bypassing a resource’s policy is otherwise trivial. See unsafe inline script for an example. Specifying nonce makes a modern browser ignore
'unsafe-inline'
which could still be set for older browsers without nonce support. - '<hash-algorithm>-<base64-value>'
- A sha256, sha384 or sha512 hash of scripts or styles. The use of this source consists of two portions separated by a dash: the encryption algorithm used to create the hash and the base64-encoded hash of the script or style. When generating the hash, don't include the <script> or <style> tags and note that capitalization and whitespace matter, including leading or trailing whitespace. See unsafe inline script for an example. In CSP 2.0 this applied only to inline scripts. CSP 3.0 allows it in the case of
script-src
for external scripts.
Examples
Violation cases
Given this CSP header:
Content-Security-Policy: worker-src https://example.com/
Worker
, SharedWorker
, ServiceWorker
are blocked and won't load:
<script> var 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 | Status | Comment |
---|---|---|
Content Security Policy Level 3 The definition of 'worker-src' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
worker-src | Chrome
Full support
59
| Edge Full support 79 | Firefox Full support 58 | IE No support No | Opera Full support 48 | Safari No support No | WebView Android
Full support
59
| Chrome Android
Full support
59
| Firefox Android Full support 58 | Opera Android Full support 45 | Safari iOS No support No | Samsung Internet Android Full support 7.0 |
Legend
- Full support
- Full support
- No support
- No support
- See implementation notes.
- See implementation notes.