Mixed content blocking in Firefox
- Revision id: 48735
- Creator: Michael Verdi
- Comment: Moved some content to a template (for use on android) https://support.mozilla.org/en-US/kb/templateaboutmixedcontent
- Reviewed: Yes
- Reviewed by: Verdi
- Is approved? Yes
- Is current revision? No
- Ready for localization: Yes
- Readied for localization:
- Readied for localization by: Verdi
When you see the shield icon in the address bar, it means that Firefox has blocked content that is insecure on the page you're visiting. We'll explain what that means and what options you have.
HTTP is a system for transmitting information from a web server to your browser. HTTP is not secure, so when you visit a page served over HTTP, your connection is open for eavesdropping and man-in-the-middle attacks. Most websites are served over HTTP because they don't involve passing sensitive information back and forth and do not need to be secured.
When you visit a page fully transmitted over HTTPS, like your bank, you'll see a green padlock icon in the address bar (see How do I tell if my connection to a website is secure? for details). This means that your connection is authenticated and encrypted, hence safeguarded from eavesdroppers and man-in-the-middle attacks.
However, if the HTTPS page you visit includes HTTP content, the HTTP portion can be read or modified by attackers, even though the main page is served over HTTPS. When an HTTPS page has HTTP content, we call that content “mixed”. The page you are visiting is only partially encrypted and even though it appears to be secure, it isn't. For more information about mixed content (active and passive), see this blog post.
What options do I have?
Most websites will continue to work normally without any action on your part.
If you need to allow the mixed content to be displayed, you can do that easily:
- Click the shield icon
in the address bar and choose Disable Protection on This Page from the dropdown menu.
- The icon in the address bar will change to an orange warning triangle to remind you that insecure content is being displayed.
To revert the previous action (re-block mixed content), just reload the page.
The icon is a gray globe despite blocking enabled
Only the potentially harmful part of HTTP content is blocked so some websites may still have HTTP content. In that case, the connection between Firefox and the website is still partially encrypted and should not be considered safe against eavesdropping, hence the gray globe icon.