Drake, Kevin Hart, LeBron James, the "Stranger Things" cast, and just about everyone else seems to be posting artificially-aged selfies on social media in the latest viral trend, called the #FaceAppChallenge. All you have to do is download FaceApp and take a photo before applying an old-age filter. But users should know that privacy concerns have emerged about the Russian-made app.

FaceApp, a startup owned by Russian company Wireless Lab, uses artificial technology to transform your photos, according to its website. With a filter, you can see what you'd look with a beard, gray hair, and even realistic-looking wrinkles. The app came out in 2017, but it recently burst into the spotlight with the aging app challenge.

As of Wednesday, the app sits on top of App Store and Google Play downloads. For a more practical popularity test, scroll through your personal social media feed and you'll likely find a friend or celebrity taking part. The result often looks like it could be a realistic portrait of the future, like this photo of Drake as a distinguished senior citizen.

There are some concerns over FaceApp's vague privacy policy, however. The app collects access to your photos, location information, usage data and browsing history. And while the app states that it won't rent or sell your information to third parties, it will share certain information with third-party advertising partners for targeted ads.

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"To make FaceApp actually work, you have to give it permissions to access your photos - ALL of them. But it also gains access to Siri and Search. Why? Not for anything good for you, I bet," Rob La Gesse, former vice president at Rackspace, wrote on Facebook Wednesday. "Oh, and it has access to refreshing in the background - so even when you are not using it, it is using you."

The other troubling aspect is where the data will be stored. According to its privacy policy, the information can be stored and processed in the U.S. or any country where FaceApp conducts its business.

"FaceApp, its Affiliates, or Service Providers may transfer information that we collect about you, including personal information across borders and from your country or jurisdiction to other countries or jurisdictions around the world," the policy states.

FaceApp said in a statement that "most images are deleted from our servers within 48 hours."

FaceApp CEO Yaroslav Goncharov tried to quell the fears Wednesday, telling the technology website TechCrunch that the app performs most of its processing in the cloud — specifically AWS and Google Cloud. He also said no user data is transferred to Russia. CBS News has also reached out to FaceApp for further comment.

This isn't the first time FaceApp has faced public scrutiny. The photo editing app came under fire in 2017 when its "hot" filter gave people light skin tones, CNET reported.