Understanding Mixed Content Warnings

A "Mixed Content" warning occurs when an HTML page loaded securely over HTTPS attempts to load resources (like images, scripts, or stylesheets) insecurely over HTTP. Modern browsers often block this insecure content or display warnings because it compromises the security of the entire page.

Why It's a Problem

Loading resources over HTTP on an HTTPS page creates security vulnerabilities:

• Passive Mixed Content (e.g., images): Browsers might display a warning but often still load the content. It opens the door for content spoofing.
• Active Mixed Content (e.g., scripts, stylesheets): An attacker could intercept and rewrite the insecure script, potentially taking full control of the page. Browsers almost always block active mixed content.

How to Fix (If You Own the Website)

• Update URLs to HTTPS: Ensure all resources are loaded via HTTPS. Manually update http:// links in your HTML to https://.
• Check Third-Party Content: Ensure embedded widgets or iframes from other sites are using HTTPS URLs.
• Implement Content Security Policy (CSP): Use the upgrade-insecure-requests CSP directive to automatically tell the browser to try loading HTTP resources over HTTPS.