CITE Sefer Chofetz Chaim chapter 6, halacha 9

The rule of thumb is anything which constitutes speaking lashon hara is also the sin of accepting lashon hara. There is no difference whether you are listening to someone talk about someone else’s misdeeds, or his family’s misdeeds whether it’s past or present or just name calling either way there is a prohibition of speaking and accepting lashon hara. However it is possible that a person who is listening to “lashon hara” will get a sin but the speaker won’t. This is in the situation where the speaker should speak up to try to help a situation but the listener is forbidden to decisively accept what he hears as truth until he does his own research and finds out himself, he just has to be concerned of the problem mentioned.

The Yad HaKetana (hilchos Deos 9:8) says that even if a person says something negative which is the truth it is still called a lie and a waste. Why is it a lie if it’s true? He says if there is no basis or purpose to what is said then granted it’s a waste but it’s even a lie since there is no purpose or even a negative purpose to say it. The Chofetz Chaim has another reason of why a true negative statement is a lie which is the effect of what you say could be a lie because if for example you speak negatively about someone’s family or what he did in the past but he’s a good guy and did teshuva now so Hashem loves him and he has a clean slate therefore it’s a lie to make people think otherwise.