I would like to open source my software library under the LGPL license. But I'm not sure if I'm allowed to use that license, as my library uses another library which is currently closed sourced. By using I mean that my library has a dependency on that closed sourced, third-party library. I won't be able to distribute the third-party library, but I hope that they will open source it some time later.
What am I allowed to do in this case?