A new lawsuit claims that Facebook and Meta kept snooping through a loophole after Apple made it harder to track user behavior outside of their own borders.

The complaint was filed in the United States District Court for the Northern District of California. Hundreds of millions of U.S. users could be affected by the proposed class-action lawsuit.

The lawsuit alleges that Meta is breaking privacy laws at the state and federal level, including the Wiretap Act, which makes it illegal to intercept electronic communications without consent. Last week, another complaint was filed.

Meta is accused of following users online by sending them to the web browser built into Facebook and injecting javascript into the websites they visit. It's possible for the company to monitor every single interaction with external websites, including where they tap and what passwords they enter.

Now, even when users do not consent to being tracked, Meta tracks Facebook users’ online activity and communications with external third-party websites by injecting JavaScript code into those sites. When users click on a link within the Facebook app, Meta automatically directs them to the in-app browser it is monitoring instead of the smartphone’s default browser, without telling users that this is happening or they are being tracked.

In April of last year, Apple introduced a new version of its operating system, callediOS 14, which made it much harder for social media companies to track users. As it prepared investors to adjust to the new normal for its ad targeting business, the company cited Apple's privacy changes as a "headwind."

The allegations are without merit and the company will defend itself vigorously. The in-app browser has been designed to respect the privacy of users.

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Apple asks if a user consents to have their activity tracked across other companies. Users who opt out might assume that they are on an external web browser when opening links within Facebook orInstagram, but the company would likely argue the opposite.

The lawsuit is based on a report by security researcher Felix Krause, who raised concerns about in-app browsers. Meta should send users to another browser to close the loophole.

Krause wrote in a post that "Do what Meta is already doing with WhatsApp: Stop modifying third party websites and useSafari or SFSafari ViewController for all third party websites." It is what is best for the user.

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