job search question

I work for a government agency (US) and I recently applied to another agency. The agency that I applied to emailed me saying that I had been tentatively selected, but they needed to collect more information before an offer was extended. They asked for my current job HR contact information, which I provided. However, before any offer was extended, my current boss confronted me about the new agency asking for a release date (when I could start the the job). I immediately contacted the new agency HR asking what was going on as my boss confronted me about the release date. The new agency HR told me that before an offer could be extended they were still collecting information (I have their SF-75 request in email format from my current boss). It turns out that what the new HR is waiting for is that they may have a priority placement candidate that they need to clear as not being qualified for the position before they offer me the position. So currently I still don't have an offer, and due to the premature contact between HR departments, my current position is very awkward for both me and my boss. Do I have any legal options in this situation or is this just something that prospective employees have to weigh out before applying to any new position?

They should not have done that if you told them to keep it confidential, and you could take action if it truly damages you.