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Enable strict MIME type checking for worker scripts
Supported versions
- Windows: ≥ 150
- macOS: ≥ 150
- Android: Not supported
- iOS: Not supported
Description
This policy controls whether strict MIME type checking is used for worker scripts.
If you enable or don't configure this policy, worker scripts use strict MIME type checking for JavaScript. Worker scripts that use legacy MIME types are rejected.
If you disable this policy, worker scripts use lax MIME type checking. This allows worker scripts that use legacy MIME types, such as text/ascii, to continue to load and run.
Browsers traditionally used lax MIME type checking, which allowed JavaScript resources to load with several legacy MIME types. This behavior can create security risks by allowing resources to load as scripts when they weren't intended to be used that way.
Microsoft Edge uses strict MIME type checking by default. Enabling this policy follows the default behavior. Disabling this policy lets admins temporarily retain the legacy behavior for compatibility.
For more information about JavaScript and ECMAScript media types, see https://html.spec.whatwg.org/multipage/scripting.html#scriptingLanguage.
Supported features
- Can be mandatory: Yes
- Can be recommended: No
- Dynamic Policy Refresh: Yes
- Per Profile: Yes
- Applies to a profile that is signed in with a Microsoft account: No
Data type
- Boolean
Windows information and settings
Group Policy (ADMX) info
- GP unique name: StrictMimetypeCheckForWorkerScriptsEnabled
- GP name: Enable strict MIME type checking for worker scripts
- GP path (Mandatory): Administrative Templates/Microsoft Edge
- GP path (Recommended): N/A
- GP ADMX file name: MSEdge.admx
Example value
Disabled
Registry settings
- Path (Mandatory): SOFTWARE\Policies\Microsoft\Edge
- Path (Recommended): N/A
- Value name: StrictMimetypeCheckForWorkerScriptsEnabled
- Value type: REG_DWORD
Example registry value
0x00000000
Mac information and settings
- Preference Key name: StrictMimetypeCheckForWorkerScriptsEnabled
- Example value:
<false/>