A website can have a valid SSL certificate, a firewall and regular backups and still benefit from another important layer of protection: HTTP security headers.
These headers are instructions sent by a web server to a visitor’s browser. They help the browser decide how to handle connections, load resources and display website content. When configured appropriately, security headers can reduce exposure to certain browser-based attacks and make a website’s security configuration more robust.
For businesses operating WordPress websites, online stores, customer portals and other web applications, understanding security headers is a useful step towards improving website security.
In this guide, we explain the most important security headers, what they do, common configuration mistakes and how Cloudflare can help businesses manage some of them.
What Are HTTP Security Headers?
When someone visits your website, the server returns a response containing the page content and metadata. HTTP response headers are part of that response and provide information about how the browser should handle it.
Some headers control caching, content types and redirects. Others provide security instructions that can restrict how a browser loads content or handles connections.
For example, a security header can instruct a browser to use HTTPS for future visits, prevent certain types of content from being interpreted incorrectly or restrict which websites can embed a page.
Security headers are not a replacement for secure application code, strong authentication or server protection. Instead, they provide an additional layer of defence that works alongside those measures.
1. HTTP Strict Transport Security (HSTS)
HTTP Strict Transport Security, commonly called HSTS, tells a browser to use HTTPS when connecting to a website for the period specified by the site’s policy.
HTTPS encrypts the connection between a visitor’s browser and the website. HSTS helps reduce the risk of certain downgrade attacks that attempt to move a visitor from a secure connection to an insecure HTTP connection.
A correctly configured HSTS policy is particularly useful for websites that consistently support HTTPS.
However, HSTS needs careful planning. If you apply it to a domain or subdomain that does not support HTTPS correctly, visitors may be unable to access that site until the policy expires or is changed. The includeSubDomains and preload options require particular caution because their effects can extend beyond the main website.
Before enabling HSTS, confirm that HTTPS works consistently across every hostname covered by the policy and that your SSL/TLS configuration is reliable.
Cloudflare supports HSTS configuration through its SSL/TLS settings. Its official documentation explains the requirements and cautions for enabling the feature.
2. Content Security Policy (CSP)
A Content Security Policy helps control which resources a browser is allowed to load for a webpage.
This is important because modern websites frequently use JavaScript, stylesheets, fonts, images and third-party integrations. If malicious code is injected into a page, a carefully designed CSP can limit which resources the browser is permitted to execute or load.
For example, a website may define trusted sources for scripts and connections rather than allowing resources from any location.
CSP can help mitigate certain cross-site scripting (XSS) and content-injection risks. However, a policy that is too broad may provide limited protection, while a policy that is too restrictive can break legitimate features such as payment integrations, analytics, chat widgets or customer portals.
The safest approach is to identify the resources your website legitimately needs, test the policy in a reporting or monitoring mode where supported, and enforce restrictions only after verifying that essential functionality continues to work.
CSP should complement secure coding and input validation, not replace them.
3. X-Content-Type-Options
The X-Content-Type-Options header helps prevent browsers from interpreting a resource as a different content type from the one declared by the server.
The commonly used value is nosniff.
This can help reduce certain risks associated with incorrect content-type handling. It is especially relevant when a website serves different kinds of resources, such as scripts, stylesheets and downloadable files.
The header is relatively simple, but it should be configured alongside correct MIME types. If your website serves resources with incorrect content types, enabling nosniff may reveal problems that need to be fixed.
4. X-Frame-Options and Clickjacking Protection
Clickjacking occurs when a user is tricked into interacting with a website through a deceptive or embedded interface.
For example, an attacker may attempt to place a legitimate page inside an invisible or disguised frame, causing a visitor to click something they did not intend to select.
The X-Frame-Options header allows a website to restrict whether other pages can embed it in a frame.
Common values include DENY, which prevents framing, and SAMEORIGIN, which allows framing by pages from the same origin.
However, some business applications legitimately use embedded pages. Before blocking framing, check whether your website relies on an integration that would be affected.
The Content Security Policy directive frame-ancestors provides a more flexible way to specify which origins may embed a page. When supported by your target browsers, it can be used to express a more specific framing policy.
5. Referrer-Policy
When visitors navigate from one page to another, browsers may send referrer information that identifies where the request originated.
The Referrer-Policy header controls how much of this information the browser sends.
A policy such as strict-origin-when-cross-origin is commonly used to limit the amount of URL information shared with other origins while retaining useful information for same-origin navigation.
This matters because URLs can sometimes contain sensitive information, although sensitive data should never be placed in URLs in the first place.
Choosing an appropriate policy helps balance privacy, functionality and analytics requirements. Test it with any integrations that depend on referral information.
6. Permissions-Policy
The Permissions-Policy header allows a website to control access to certain browser features, such as camera, microphone and geolocation capabilities.
For example, a business website that does not use a visitor’s camera may be able to restrict access to that feature.
The appropriate policy depends on what the application actually needs. A video-conferencing service, for instance, may legitimately require microphone and camera access.
Permissions-Policy is not a universal defence against website attacks. Its purpose is to restrict selected browser features where appropriate, helping reduce unnecessary access and improve the website’s security posture.
How Can You Check Your Website’s Security Headers?
Before changing your configuration, find out which headers your website already sends.
You can use your browser’s developer tools to inspect the network response for a page. Look at the response headers returned by the server or the reverse proxy in front of it.
You can also use a reputable HTTP header testing service to review the headers visible to a visitor.
Check important pages rather than relying only on the homepage. Different applications, subdomains and response types may use different configurations.
Remember that seeing a header does not automatically mean the website is secure. A Content Security Policy may be too permissive, an HSTS policy may not cover the intended hostnames, or a header may conflict with an essential website feature.
The goal is to confirm that the headers are present where needed, correctly configured and compatible with the application.
Common Security Header Mistakes
One common mistake is copying a collection of security headers from another website without understanding how they work. A policy suitable for a static website may break a complex application that relies on third-party scripts.
Another mistake is assuming that a security-header testing score is a complete measure of website security. Headers cover only some browser-related risks; they do not prove that the website’s software, accounts, database or server is secure.
Businesses should also avoid enabling HSTS preload or applying a policy to every subdomain before verifying HTTPS across the entire domain structure.
Finally, security headers should be reviewed when the website changes. Adding a new payment integration, content delivery service or application component may require an adjustment to an existing policy.
A measured approach—inventory, configuration, testing and monitoring—is more reliable than applying every possible header without considering the consequences.
Can Cloudflare Configure Security Headers?
Cloudflare can help manage certain HTTP response headers for websites that are proxied through its network.
Depending on the available products and configuration, response-header transform rules or other Cloudflare capabilities can be used to add or modify selected headers. HSTS can also be configured through Cloudflare’s SSL/TLS settings.
This means some header configuration can be managed at the edge rather than being implemented solely on the origin server.
However, not every header is automatically enabled, and Cloudflare does not make every website secure simply by being activated. The correct configuration still depends on the application’s requirements and the risks being addressed.
Content Security Policy deserves particular attention because it can interfere with legitimate scripts and integrations when configured incorrectly. Test changes before enforcing restrictive rules on a production website.
For technical details, refer to Cloudflare’s official documentation on HTTP security headers, HSTS and Content Security Policy.
How Tremhost Can Help With Website Protection
Businesses that want help configuring website protection can explore Tremhost’s Cloudflare-based security services.
Armor Guard is Tremhost’s Cloudflare Pro-based website protection offering. It is an option for businesses looking to add Cloudflare technology and configuration assistance to their website security arrangements.
For broader requirements, Armor Shield offers a higher-tier managed security service. The appropriate option depends on the website, the level of assistance required and the current scope of each plan.
Before purchasing, confirm whether security-header configuration is included, which tasks are covered and whether application-specific testing is available. Do not assume that every security header is automatically enabled by a Cloudflare subscription.
You can compare the available offerings on the Tremhost Cloudflare services page.
Conclusion
HTTP security headers are a useful part of a website’s defence-in-depth strategy. They allow browsers to apply important instructions about secure connections, resource loading, content types, framing and selected browser capabilities.
Their value depends on correct configuration. Poorly designed policies can disrupt legitimate functionality, while the presence of headers alone does not guarantee that a website is secure.
Review the headers your website currently sends, understand the risks each one addresses, test changes carefully and revisit the configuration as your website evolves.
Combined with secure software, strong authentication, reliable hosting and suitable traffic protection, well-configured security headers can help strengthen your website’s overall security.
