Here's the deal: If you own a Samsung phone, including the Galaxy S9 or the Note 8, your private pictures may be compromised. The phone may send photos to your contacts without your knowledge, which is not a big deal until you find that certain pictures may not be sent to specific contacts. In other words, your phone could send files to your boss or mother, which of course would be a big deal.
The cause of the problem is unknown at this time, and Samsung is investigating the matter. While you wait, there are corrections if you are one of the victims.
Contributions to Reddit and Samsung's Forums, first reported by Gizmodo explain that everything happens without the owner's knowledge. The photos are randomly sent to the contacts, and there is no trace in the Samsung Messages app to prove that it happened. The only proof is the answer you get from a recipient who is surprised to see pictures of you without explanation.
A Reddit user has discovered that Samsung messages sent his entire photo gallery to a contact in the middle of the night. Fortunately, it was the user's partner, but the behavior is still unacceptable.
Samsung says it's investigating the matter:
We are aware of the reports and our technical teams are investigating it. Affected customers are kindly requested to contact us directly at 1-800-SAMSUNG.
One theory why this happens is that Samsung Messages does not work correctly with the RCS profile updates that were recently introduced. According to T-Mobile, this is not a T-Mobile issue that points to Samsung.
While you're waiting for Samsung to fix the problem, you can try two temporary fixes yourself. First and foremost, you can drop Samsung messages and use another messaging app. Second, you should revoke the permissions of Samsung Messages to access your phone's memory. In any case, you should remove for security even more compromising photos from your Galaxy smartphone.