Angela Lang/CNET

When you're scrolling through Facebook's app, the social network could be using your camera, concerned users have found. Multiple people have found and reported that their iPhone cameras were turned on in the background while they were looking at their feed.

The issue came to light through several posts on Twitter. Users noted that their cameras were activated behind Facebook's app as they were watching videos or looking at photos on the social network.

After people clicked on the video to full screen, returning it back to normal would create a bug in which Facebook's mobile layout was slightly shifted to the right. With the open space on the left, you could now see the phone's camera activated in the background.

This was documented in multiple cases, with the earliest incident on Nov. 2.

Today, while watching a video on @facebook, I rotated to landscape and could see the Facebook/Instagram Story UI for a split second. When rotating back to portrait, the Story camera/UI opened entirely. A little worrying... pic.twitter.com/7lVHHGedGf — DFC (@neo_qa) November 2, 2019

It's since been tweeted a couple other times, and CNET has also been able to replicate the issue.

Facebook app on iOS 13.2.2 opens my phone’s rear camera when I open a profile photo swipe down to return (look at the little slit on the left of the video). Is this an app bug or an iOS bug?? @facebook @AppleSupport pic.twitter.com/WlhSXZulqx — Daryl Lasafin (@dzlasafin) November 10, 2019

Guy Rosen, its vice president of integrity, tweeted Tuesday that this seems like a bug and the company's looking into the matter.

Thanks for flagging this. This sounds like a bug, we are looking into it. — Guy Rosen (@guyro) November 12, 2019

In another tweet, Rosen said that Facebook is submitting a fix to the App Store on Tuesday.

"We recently discovered our iOS app incorrectly launched in landscape," Rosen said. "In fixing that last week in v246 we inadvertently introduced a bug where the app partially navigates to the camera screen when a photo is tapped. We have no evidence of photos/videos uploaded due to this."

Rosen later confirmed that Facebook didn't capture any photos or videos while in the background, noting that it was in preview mode.

Daryl Lasafin, the creative director of marketing agency Dame Digital in the Philippines, said he dismissed the issue when he first noticed it Sunday morning, thinking it was a minor glitch. Then, as he continued using Facebook's app throughout the day, he couldn't help but notice his camera kept being activated in the background.

"I thought it was just my phone or the app acting up," Lasafin said in a direct message. "Then I observed it became more persistent that evening."

He tried troubleshooting it himself, uninstalling and reinstalling the app, as well as removing Facebook's access to the camera. The camera still popped up after all that, but after he revoked permissions from Facebook, it was just a black screen, Lasafin said.

The bug appears to only affect the latest iOS versions, and it didn't happen on Android devices. The Next Web reported that the bug didn't appear on iOS 12.

The active camera could become another unwanted privacy flap for Facebook, which in July agreed to pay a record $5 billion fine for failing to protect people's data. Facebook's track record with privacy doesn't help the massive social network's image, though it doesn't seem to have hurt its growth in users or revenue.

Now playing: Watch this: Zuckerberg gets grilled on Capitol Hill

Facebook's reputation on privacy is so worrying that many people still believe the social network is secretly recording people through their microphones.

The camera bug won't do the company any favors in dispelling that myth. While Facebook's app users do give the company permission to use their camera and microphone, there's no reason it needs to be activated while a person is simply scrolling through the feed or watching a video.

"I gave the Facebook app permission to access my camera to fully use the My Day / Stories feature and upload photos and videos as status," Lasafin said. "But at the time, evidently, I wasn't using the app for anything that requires camera access."

He said he's since deleted Facebook's app, out of privacy concerns with the company. He's not sure if he'll reinstall the app once the issue is addressed.

Originally published at 7:49 a.m. PT.

Updates, 8:43 a.m. PT: Added tweet from Facebook's vice president of integrity. 11:08 a.m. PT: To add more details on the bug from Facebook. 2:56 p.m. PT: With additional update from Facebook.