We got a security vulnerability reported for Play versions between 2.6.12 and 2.6.15. Details here:
Only the versions above were affected, so if you are using one of them and deploying your application on Windows, you need to update now. Play 2.6.16 is binary compatible with 2.6.12-2.6.15, so it should be just a matter of update the version and re-deploy.
Thanks to Qihoo360 Redteam for reporting the problem.