I have a shower drain (25+ year old house) that is leaking into the ceiling. I've cut the ceiling and determined the leak is coming from the top most part of this drain:
Attachment 12635

From the top of the shower, you'll see the drain is embedded into the tile - the debris is the remnants of a failed attempt to caulk the edge of the drain. It looks to me that the drain is embedded in the tile and cement that builds of the pan and tile. How should I attempt to repair this on my own? Thanks!
Attachment 12636

From you posted photos, it appears to me you don't have proper shower drain head. That's the cause of your leak.

Here is what's happening: Shower drain should have 3 holes in the side of it to accommodate condensation run off. Every time you turn hot water on, and hot water hits the tiled shower floor, it immediately creates condensation under the tile. If that condensation has no place to go, it then travels to the hole in the plywood cut around the drain - and down to your ceiling.

Solution: break up shower floor. Install proper drain. Water proof shower floor ( hot mop or PVC liner ). Test for leaks. Install bed of new concrete and tile over it.

Thanks for the quick answer Milo!

Most of these houses have a lead shower pan under the tile - I think I see part of the pan ( the black area next to the hole in the plywood ).

When I run the shower with cold water, I can feel moisture coming from the top of the pvc pipe where it meets at the top.

Do you still recommend breaking up the shower floor to fix the leak?

Thanks!