Referrer-Policy is a security header that controls how much referrer information is sent when a user navigates from one website to another. The referrer information typically includes the URL of the previous page, which can sometimes expose sensitive data, such as user sessions, authentication tokens, or internal site structures.
Why Does the Site Need Referrer-Policy?
- Without this header, a website may leak private information when users click outbound links. This could lead to:
- Exposure of sensitive URL parameters (e.g., session IDs, authentication tokens).
- Unintended data sharing with third-party sites.
- Privacy concerns, especially for users browsing on secure sites that link to external pages.
By defining a strict Referrer-Policy, websites can limit the data sent to external domains, reducing privacy risks and preventing potential security leaks.
What Does It Mean If a Site Lacks Referrer-Policy?
- The site may leak internal URLs or user session details when linking to other websites.
- Users navigating from an HTTPS page to an HTTP page may unknowingly expose private browsing details.
- Advertisers, analytics platforms, and third-party trackers can collect more user data than necessary.
How Should You Proceed If Referrer-Policy Is Missing?
- Be cautious when clicking links that take you from a secure page (HTTPS) to an insecure one (HTTP).
- Avoid sharing sensitive URLs that include authentication tokens or personal identifiers.
- If you manage a website, configure a strict Referrer-Policy to prevent unnecessary data exposure.
FAQs
What are the different values for Referrer-Policy?
`no-referrer` – No referrer information is sent.
`no-referrer-when-downgrade` – No referrer is sent when moving from HTTPS to HTTP.
`same-origin` – Referrer data is only sent to the same origin.
`strict-origin` – Only the origin is sent, and no data is leaked to less secure protocols.
`strict-origin-when-cross-origin` – Sends full referrer data within the same site but limits it for external domains.
How does Referrer-Policy improve privacy?
It prevents unnecessary data exposure when users navigate between sites, limiting tracking and reducing the risk of leaking sensitive URLs.
Can a website be secure without Referrer-Policy?
While other security measures help, missing this header may allow excessive data sharing, creating potential privacy concerns.
How do I check if a website has Referrer-Policy?
Use browser developer tools or online security scanners to inspect the response headers. If set, you will see `Referrer-Policy: strict-origin-when-cross-origin` or another value in the response.
Should website owners add Referrer-Policy if it’s missing?
Yes, especially for sites handling private user data, financial transactions, or authentication sessions. A strict policy helps limit exposure and enhances user privacy.