Third-party tracking cookies are now blocked for all users by default. See Content blocking for more information about how Firefox protects you against tracking.

Cross-site tracking cookies are now blocked for all users by default. See Enhanced Tracking Protection for more information about how Firefox protects you against tracking.

Third-party cookies are cookies set by a website other than the one you are currently on. For example, cnn.com might have a Facebook like button on their site. That like button will set a cookie that can be read by Facebook. That would be considered a third-party cookie.

Some advertisers use these types of cookies to track your visits to the various websites on which they advertise. If you are concerned about this, you can disable third-party cookies in Firefox.

Note: Disabling third-party cookies in Firefox can stop some types of tracking by advertisers, but not all. If you are concerned about tracking, see also How do I turn on the Do Not Track feature? and What happened to tracking protection? and Content blocking, Enhanced Tracking Protection in Firefox for desktop and Trackers and scripts Firefox blocks in Enhanced Tracking Protection.

Third-party cookie settings are available in the Settings page's Privacy & Security panel:

In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
Select the Privacy & Security panel and go to the Cookies and Site Data section.
From the drop-down next to Accept third-party cookies and site data, select Never.
Note: After browsing with this setting, you won't be able to properly view some of your favorite websites, so an intermediate solution is to set it to From visited. That will allow third-party cookies coming from previously visited websites.
Close the Settings page. Any changes you've made will automatically be saved.

Disable third-party cookies

To block third-party trackers or all third-party cookies:

Click the Firefox menu button The image "fx57menu" does not exist. and select Content Blocking.
- This takes you to the Content Blocking section of your Firefox Settings Privacy & Security panel.
Select the Third-Party Cookies checkbox to block third-party tracking cookies. To block all third-party cookies, change the setting from Trackers (recommended) to All third-party cookies (may cause websites to break).

Note: If the checkbox is already selected and you see the message Your settings in Cookies and Site Data are preventing changes to Third-Party Cookies settings, click Change Cookie Settings.

This takes you to the Cookies and Site Data section of Firefox OptionsPreferences, where you can change the type of cookies blocked.

Click the Firefox menu button The image "fx57menu" does not exist. and select Content Blocking.
This takes you to the Content Blocking section of your Firefox Settings Privacy & Security panel.
Select the Custom radio button to choose what to block.
Select the Cookies checkbox. Third-party trackers is the default setting.

To block all third-party cookies, select All third-party cookies (may cause websites to break) from the drop-down.
Close the Settings page. Any changes you've made will automatically be saved.

In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
Select the Privacy & Security panel.
Under Enhanced Tracking Protection, select the Custom radio button to choose what to block.
Select the Cookies checkbox. Cross-site and social media trackers is the default setting.

To block all third-party cookies, select All third-party cookies (may cause websites to break) from the drop-down.
Close the Settings page. Any changes you've made will automatically be saved.

Enable third-party cookies for specific sites

Some websites may not work properly when third-party cookies are blocked, even with the Trackers (recommended)Third-party trackers setting. To enable third-party cookies for specific websites:

Click the Control Center button in the address bar and click Disable Blocking for This SiteTurn off Blocking for This Site

For more information, see Turn Content Blocking off on individual sites.

Some websites may not work properly when third-party cookies are blocked, even with the Cross-site and social media trackers setting.

To turn off Enhanced Tracking Protection for a specific website:

Visit the website.
Click on the shield to the left of the address bar.
Toggle the switch at the top of the panel.
This will turn off Enhanced Tracking Protection for this site. The page will reload automatically and allow trackers on this site only.