Serve security.txt as text/plain with utf-8 on nginx

Why it matters

RFC 9116 requires the file to be sent as text/plain in utf-8. Tools may reject it if the server labels it as html, binary or another charset.

The fix

1. Serve the file from an exact-match location that sets the type and charset, inside the server block for example.com.
2. Run nginx -t and reload nginx, then check the Content-Type header again.

location = /.well-known/security.txt {
    root /var/www/security;
    default_type text/plain;
    charset utf-8;
}

The examples use example.com. Replace it with your own domain.

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Related

• Reported by the security.txt check
• Publish a security.txt file
• Serve security.txt from /.well-known/
• Serve security.txt over https
• Add a Contact line to security.txt
• Fix the Contact value in security.txt
• Add an Expires line to security.txt
• Use an RFC 3339 date in the Expires line
• Renew the expired security.txt
• Renew security.txt before it expires
• Shorten the security.txt Expires date
• Fix repeated or insecure fields in security.txt
• Make the Canonical line match where the file is served