People are reporting that the latest version of Samsung Messages has a very serious bug on the Galaxy S9, Galaxy S9+, and Galaxy Note 8. It may be sending your photos to others without you knowing it.
Reports claim that certain photos that have already been sent are being sent again to people in the Messages app. Some even report that entire galleries are being sent over text message. The biggest issue is that the app won’t show that anything has been sent, so you’d never know it happened unless the recipient tells you. Carrier logs will of course show that it happened.
If you haven’t updated the app, don’t do so until Samsung fixes the issue. It might be a while because the company hasn’t acknowledged it so far. If you already have, head to Settings > Apps, select Samsung Messages, and disable the storage permission for it so it can’t access your photos. Better yet, switch to a different messaging app in the meantime (or permanently). Android Messages now supports sending texts on your computer, so you can give that a shot!