I've turned in my resignation and will be leaving the company soon. I was the last member of the original development team (and the lead) for our project, so new people are being moved to the project to take over. The replacement programmer for this project has been with the company for years and seems well respected.
The new programmer has been asking me some questions and writing some code over the last few days, and they sent in a first pull request this week.
After review, it turns out there's a rather massive security issue with the code. It's on such a level that I would expect even fresh programmers to know better. (the gist of it: they put the root credentials for a backend server in the javascript client-side code so the client could load some client-data from a backend server that doesn't support user accounts. That backend is normally accessed through a second backend which does support specific user accounts, and handles making sure only the right data is loaded.)
The system contains quite a bit of sensitive data, and if this code had made it into production, the company could get in serious trouble. Now, I caught the issue and nothing happened, but this programmer will become the lead when I'm gone and I fear they might make another mistake like this.
Should I issue a warning to management about what might happen after I leave, or is this more of a "not your problem" situation and is warning them about these things more of a faux-pas?