Are you sure its not just defrosting drips. The pipe looks covered in drops of water.
I don't see how that top one could be leaking as its a socket and also above the flood level.
Do you have any appliances above the access branch that you've shown. If not I'd be surprised if the joints illustrated are leaking as they are otherwise in the dry section of the soil stack. Are your appliances emptying okay? If they are I think Norcon's response is your answer
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