Dries Buytaert

HTTP Headers Analyzer

2 / 10
https://www.cnn.com
Website → Varnish → Browser
7 missing headers, 5 warnings, 3 notices
Header
Value
Explanation
content-security-policy
default-src 'self' blob: https://*.cnn.com:* http://*.cnn.com:* *.cnn.io:* *.cnn.net:* *.turner.com:* *.turner.io:* *.ugdturner.com:* courageousstudio.com *.vgtf.net:*; script-src 'unsafe-eval' 'unsafe-inline' 'self' *; style-src 'unsafe-inline' 'self' blob: *; child-src 'self' blob: *; frame-src 'self' *; object-src 'self' *; img-src 'self' data: blob: *; media-src 'self' data: blob: *; font-src 'self' data: *; connect-src 'self' data: *; frame-ancestors 'self' https://*.cnn.com:* http://*.cnn.com https://*.cnn.io:* http://*.cnn.io:* *.turner.com:* courageousstudio.com;
The Content Security Policy (CSP) header helps prevent cross-site scripting (XSS), clickjacking, and other code injection attacks by specifying which dynamic resources are allowed to load.
default-src sets the default policy for fetching resources like JavaScript, images, CSS, fonts, AJAX requests, frames, HTML5 media.
script-src specifies valid sources for JavaScript. This includes not only URLs loaded directly into <script> elements, but also things like inline script event handlers (onclick) and XSLT stylesheets which can trigger script execution.
object-src defines what <object>, <embed> and <applet> elements are allowed to be loaded and executed.
style-src defines what CSS stylesheets are allowed to be loaded.
media-src defines what <audio>, <video> and <track> elements are allowed to be loaded.
img-src defines what images and favicons can be loaded.
font-src defines what fonts can be loaded using CSS's font-face.
frame-src defines what <frame> and <iframe> elements can be loaded.
frame-ancestors defines what parents may embed a page using <frame>, <iframe>, <object>, <embed> or <applet>.
child-src defines what <frame>, <iframe> or workers can be loaded.
Notice Consider adding the upgrade-insecure-requests directive to automatically upgrade HTTP requests to HTTPS, helping to prevent mixed content issues.
cache-control
max-age=60
max-age specifies the maximum amount of seconds a page is considered valid. The higher max-age, the longer a page can be cached.
Notice A max-age of 60 seconds is short, especially if your content doesn't change frequently. Consider increasing max-age unless the URL has live updates.
x-last-modified
thu, 03 jul 2025 23:53:28 gmt
access-control-allow-origin
*
Indicates whether a browser can share this resource with other code. * is a wildcard. It means the browser will allow code from any origin to access this resource.
x-content-hub
build-env=prod; unique-deployment-key=rn06256h; build-version=v6.6.15-0-g4bc22af67b; build-commit-hash=4bc22af67be7ccafc548f9614aebf2f41227c6d8
x-xss-protection
1; mode=block
This header enables the browser's built-in XSS protection. However, it's considered legacy and modern browsers may ignore it.
1 enables the browser's cross-site scripting (XSS) filtering.
mode=block instructs the browser to block the response if a XSS attack is detected, instead of sanitizing the page.
x-content-type-options
nosniff
The X-Content-Type-Options header, when set to nosniff, prevents MIME type sniffing. This enhances security by ensuring browsers respect the declared Content-Type of the response, mitigating MIME confusion attacks.
The value nosniff is correctly set, providing protection against MIME type sniffing attacks.
content-type
text/html; charset=utf-8
The type of the message body, specified as a MIME type.
accept-ranges
bytes
Used by the server to advertise its support of partial HTTP requests. The browser can ask for a range or subset of the response body. It's a feature that allows a browser to resume an interrupted download. bytes is the only range unit currently supported. none means that the server does not support range requests.
date
fri, 04 jul 2025 00:27:34 gmt
The date and time at which the request was made. A browser uses it for age calculations rather than using its own internal date and time; e.g. when comparing against Max-Age or Expires.
via
1.1 varnish
The Via header tracks how a page is forwarded from proxy to proxy. Beware, not all proxies append themselves to the Via header.
age
2024
The time in seconds that the page has been in the shared proxy cache. The maximum age is set by max-age or s-maxage in the Cache-Control header.
x-served-by
cache-iad-kcgs7200080-iad, cache-iad-kjyo7100097-iad
Fastly's shield and edge servers that were queried for the request.
x-cache
miss, hit
The page was served from a cache.
x-cache-hits
0, 1
The number of times this page has been served from the Varnish cache. Higher numbers are better.
x-timer
s1751588854.197403,vs0,ve10
Provides timing information about the journey of a request through Fastly's network. Format: s<timestamp>,vs<seconds>,ve<seconds>, where s is the start time of the request, ve stands for Varnish start and ve stands for Varnish end. The length of the trip is ve - vs milliseconds.
vary
accept-encoding,origin,accept-language
The Vary header specifies a list of headers that must be considered when caching responses. For a cached response to be used, these headers must match between the cached response and the new request. This ensures that the appropriate version of a resource is served based on factors like language, encoding, or device type.
alt-svc
h3=":443";ma=86400,h3-29=":443";ma=86400,h3-27=":443";ma=86400
The alt-svc header advertises alternative services for accessing the same resource, enabling protocol negotiation and potential performance improvements.
h3 indicates that HTTP/3 is supported. Variants like h3-29 refer to specific drafts of the HTTP/3 protocol.
ma=86400 specifies that the alternative service information is fresh for 86400 seconds.
ma=86400 specifies that the alternative service information is fresh for 86400 seconds.
ma=86400 specifies that the alternative service information is fresh for 86400 seconds.
content-length
3595111
The size of the message body, in bytes.
strict-transport-security
missing Add a Strict-Transport-Security header. The Strict-Transport-Security header or HSTS header is used to instruct browsers to only use HTTPS, instead of using HTTP. It helps enforce secure communication.
referrer-policy
missing Add a Referrer-Policy header. When a visitor navigates from one page to another, browsers often pass along referrer information. The Referrer-Policy header controls how much referrer information a browser can share. This is important to configure when private information is embedded in the path or query string and passed onto an external destination.
permissions-policy
missing Add a Permissions-Policy header. Restrict access to device features like the camera, microphone, location, accelerometer and much more.
cross-origin-embedder-policy
missing Add a Cross-Origin-Embedder-Policy to specify how this page can be loaded by cross-origin resources.
cross-origin-opener-policy
missing Add a Cross-Origin-Opener-Policy header to opt-in into better browser isolation.
cross-origin-resource-policy
missing Add a Cross-Origin-Resource-Policy header to specify who can load this page.
x-permitted-cross-domain-policies
missing Add a X-Permitted-Cross-Domain-Policies header to prevent Flash, Adobe Reader and other clients from sharing data across domains.

Questions or feedback? Email dries@buytaert.net.