No, it's not a vulnerability for FireFox, it has to do with the lack of active FireFox developers. There is a group of six working on the project, but 4 of them are AWOL (absence without leave). So only 2 remain, and only one of them makes code reviews. You can say that the FireFox program is heavily undermanned. Mike Conner, one of the developers of FireFox have focused on this problem.
It's a bad period for FireFox to deal with this program, the program is still gaining popularity, but when no one is on the developing site, the program can lose popularity when patches or updates are needed.
The dates on the roadmap for FireFox 2.0 could be delayed. Conner is not optimistic for the future, however a solution could be to take some developers from the Mozilla Foundation, we hope that they will find a solution soon.