Passing on a rumor “just so you know” still makes you the delivery driver.

Framing matters less than you think. Adding that you are only mentioning it, or that you heard it from someone else, does not change the fact that the story travelled further because of you. Everyone in the chain gets to feel innocent, which is exactly how something unverified reaches a hundred people with nobody responsible for it.

Before you forward something about a person, ask whether you would say it with them standing there. Ask who it helps. If the honest answer is that it is interesting rather than useful, let it stop with you.