Headers Security
medium Severity
Free Check
X-Content-Type-Options Header
Prevents browsers from MIME-sniffing a response away from the declared content-type, stopping script execution from uploads.
Why It Matters
If an attacker uploads an image file containing JavaScript, MIME-sniffing could execute it as executable code in the victim’s browser.
How We Check This
We check if X-Content-Type-Options is sent with the exact value nosniff.
How to Fix & Implement
Copy-paste configuration blocks tailored for your web server or edge proxy.
nginx snippet
add_header X-Content-Type-Options "nosniff" always;
Frequently Asked Questions
What is MIME-sniffing?
MIME-sniffing is when a browser inspects file bytes instead of relying on the Content-Type header to guess its type.