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How to add Referrer-Policy on IIS

Last updated · Reviewed by a CISSP-certified security practitioner

To add Referrer-Policy on IIS, set the header in web.config with the value strict-origin-when-cross-origin. Limits how much of your URLs leak to other sites. Save web.config; IIS applies it on the next request. Recycle the app pool if needed. Then confirm it with curl -I or a free FixSecurityHeaders scan.

What does Referrer-Policy do?

Referrer-Policy controls what URL information the browser sends to other sites when users click links or load resources.

Risk if missing: Full URLs — including reset tokens, search terms or internal paths — can leak to third parties.

What is the IIS configuration?

Add this to web.config:

web.config
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <httpProtocol>
      <customHeaders>
        <add name="Referrer-Policy" value="strict-origin-when-cross-origin" />
      </customHeaders>
    </httpProtocol>
  </system.webServer>
</configuration>

How do I add it step by step?

  1. Open web.config.
  2. Paste the Referrer-Policy configuration shown below.
  3. Save web.config; IIS applies it on the next request. Recycle the app pool if needed.
  4. Run curl -I https://yourdomain.com and look for the referrer-policy line.
  5. Scan your site on FixSecurityHeaders to confirm the grade improved.

How do I verify it worked?

terminal
curl -sI https://yourdomain.com | grep -i "referrer-policy"
# expected:
# referrer-policy: strict-origin-when-cross-origin

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What are the common mistakes?

  • no-referrer is stricter but can break analytics attribution and some payment flows.
  • Headers in web.config apply to every response from that site.
  • Removing the Server header requires removeServerHeader (IIS 10+) or URL Rewrite.

Quick reference

HeaderReferrer-Policy
Recommended valuestrict-origin-when-cross-origin
StackIIS
Whereweb.config
ComplianceOWASP ASVS V14.4.6, SOC 2 CC6.7

FAQ

What value should I use for Referrer-Policy?

A safe default is strict-origin-when-cross-origin. no-referrer is stricter but can break analytics attribution and some payment flows.

Why isn't Referrer-Policy showing up on IIS?

Headers in web.config apply to every response from that site. Also clear any CDN or page cache, and check you edited the config that actually serves your domain.

Does Referrer-Policy affect SEO or performance?

No measurable performance cost — it's a few bytes per response. It doesn't affect rankings directly, but a misconfigured policy can break page resources, so test before enforcing.

Which compliance frameworks reference Referrer-Policy?

OWASP ASVS V14.4.6, SOC 2 CC6.7.

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