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Version: v1

Missing X-Content-Type-Options Header

Missing X-Content-Type-Options Header

What is it?

The API endpoint or server returned a response without the X-Content-Type-Options header being set correctly.

The Anti-MIME-Sniffing header X-Content-Type-Options was not set to ’nosniff’. This allows older versions of Internet Explorer and Chrome to perform MIME-sniffing on the response body, potentially causing the response body to be interpreted and displayed as a content type other than the declared content type. Current (early 2014) and legacy versions of Firefox will use the declared content type (if one is set), rather than performing MIME-sniffing.


Test case FAQs

When is this test case applicable?

This is applicable for all API endpoints when the Baseline security category is enabled in test plans.

How does it work?

Responses sent by the API server are analyzed for the missing or incorrectly set X-Content-Type-Options header.

What is the solution?

Ensure that the API server sets the Content-Type header appropriately, and that it sets the X-Content-Type-Options header to 'nosniff' for all responses. If possible, ensure that the end user uses a standards-compliant and modern web browser that does not perform MIME-sniffing at all, or that can be directed by the API server to not perform MIME-sniffing.