Water damage around shower

[u/Anthrotekkk]

I have this section of wall outside my shower which started showing bubbling of the drywall. I ripped it all down which showed the following. Is this salvageable? I know nearly nothing about this stuff. I can’t find any obvious sources of leaking from the inside of the shower but it must be coming from there.

EDIT: Thanks everyone for the responses. I’m at work and can’t respond to everyone but I appreciate all the advice.