lowSeverity: lowRisk ratingHow usable this gap is to an attacker. Severity sets the posture penalty: critical −40, high −20, medium −10, low −4, info −1. Higher severity means fix it sooner.Netlify headers (netlify.toml / _headers)Where it livesImplementationThis fix is applied in: Netlify headers (netlify.toml / _headers). That's the surface you'll edit, DNS, response headers, or a static file.~3 minTime to fixEffortRoughly 3 minutes of hands-on work, propagation aside. Most of these are copy-paste.+4 posture+4 postureScore impactPoints this fix recovers in the ApeCyber posture score (0–100). Posture = 100 minus the severity penalty of every open finding; clearing this finding adds these points back.

X-Content-Type-Options: stop the browser from guessing a file's type

One nosniff header makes browsers honor the content type you declared instead of second-guessing it

The threat

Our scanner saw your responses come back without X-Content-Type-Options: nosniff. Without that header, browsers are allowed to “sniff”: to ignore the Content-Type you sent and instead guess a file’s type from its first bytes. Most of the time the guess is harmless. Sometimes it is not.

Here is where it bites. A file a visitor uploads (a profile image, a document) that quietly contains script markup can be re-interpreted by the browser as HTML or JavaScript and run in your site’s context, even though you served it as an image. On its own that is a small crack, but it is exactly the kind of thing that turns a minor upload or content bug into a working cross-site-scripting hole. nosniff shuts the guessing off: the browser trusts the type you declared, full stop.

The exact fix

Send X-Content-Type-Options: nosniff on every response. On Netlify, add it in netlify.toml:

# netlify.toml
[[headers]]
  for = "/*"
  [headers.values]
    X-Content-Type-Options = "nosniff"

Or the Netlify _headers form:

/*
  X-Content-Type-Options: nosniff

On nginx:

add_header X-Content-Type-Options "nosniff" always;

On Apache:

Header always set X-Content-Type-Options "nosniff"

One gotcha: nosniff makes the browser trust your Content-Type exactly, so your server has to send the right one. Static hosts and Netlify already do (.js as application/javascript, .css as text/css). If a script or stylesheet stops loading right after you add nosniff, the real bug is a wrong Content-Type on that file, fix the type, do not remove the header.

Verify it

curl -sI https://yourdomain.com | grep -i x-content-type-options

A correct result is a single line: x-content-type-options: nosniff.

Proof

apecyber.com sends nosniff on every response as part of the hardened header set behind its A / 100 grade on Netlify. The ApeCyber scanner flags the missing header passively on every scan, from the outside, touching nothing. Adding it is a clean −4 off the posture score, and it takes about three minutes.