How to Fix: X-Content-Type-Options set

X-Content-Type-Options set is an important SEO check in the Security & Trust category. This is a medium-priority issue. While not urgent, it is genuinely a five-minute fix with no downside — the kind of hardening I would just do rather than debate.

What is This Check About?

This check verifies that your site sends the X-Content-Type-Options: nosniff HTTP response header. That header tells browsers to trust the declared content type of a file and stop trying to guess it. Without it, some browsers will “sniff” a file’s contents and decide, for example, that something you served as plain text is really executable script — which is exactly the loophole certain attacks rely on.

It is a small, well-established security header. Nothing on your site breaks by adding it, and it closes off a class of MIME-confusion attacks.

Why Does This Matter for SEO?

Security headers are part of how search engines and users gauge whether a site is trustworthy:

• It helps prevent MIME-sniffing attacks that can turn an uploaded file into an execution vector
• A well-hardened site is less likely to be compromised, and a hacked site is an SEO catastrophe — blacklisting, warnings, lost rankings
• Security headers show up in the site-quality audits and trust assessments many tools run
• Protecting users keeps the trust that a healthy search presence is built on

How to Check This Issue

Confirm whether the header is present:

1. Open browser DevTools, load your site, and inspect the response headers on the Network tab
2. Look for X-Content-Type-Options: nosniff in the list
3. Or run your domain through a free security-headers scanner for a full report
4. Check both the front end and, if relevant, admin and subdomain responses

How to Fix This in WordPress

Difficulty Level: EASY – This fix is straightforward and can typically be completed by anyone with basic WordPress knowledge.

Estimated Time: 5 min

Pick whichever of these matches how your site is hosted. You only need one.

Option A: Use a Security Plugin

The simplest path. Plugins like Really Simple Security, or a headers-focused plugin, let you enable X-Content-Type-Options: nosniff from a settings screen with a single toggle — no server config, no risk of a syntax typo taking the site down.

Option B: Add It at the Server

If you manage the server, set the header directly. On Apache, add Header set X-Content-Type-Options "nosniff" to your .htaccess or virtual host. On Nginx, add add_header X-Content-Type-Options "nosniff" always; to the server block. Back up the config first and reload after the change.

Step 3: Verify

1. Clear your WordPress cache if you’re using a caching plugin
2. Reload and re-inspect the response headers, or re-scan, and confirm nosniff is now present
3. Re-run the SEO Roadmap audit to confirm the issue is resolved

Recommended Tools & Plugins

These tools can help you fix and prevent this issue:

• Yoast SEO – Comprehensive SEO plugin with built-in checks
• Rank Math – Feature-rich SEO plugin with detailed analysis
• Google Search Console – Free tool to monitor your site’s search presence
• SEO Roadmap – Complete SEO audit and action plan tool

Common Mistakes to Avoid

• Editing server config with no backup and no way to roll back a bad edit
• Adding the header in two places (plugin and server) so it is sent twice
• Setting it only on the front end and leaving other responses uncovered
• Assuming this one header is “security done” — it is one of several worth having

Need More Help?

If you’re still having trouble, consider:

• Reviewing the other recommended security headers while you are in there (Strict-Transport-Security, X-Frame-Options, Content-Security-Policy)
• Asking your host whether they can set security headers at the platform level
• Consulting a WordPress developer or security specialist for a full hardening pass
• Running a complete site audit with SEO Roadmap for a prioritized action plan

This guide is part of the SEO Roadmap knowledge base – your complete resource for WordPress SEO optimization.