たこすけ さん お知らせありがとうございます。
https://www.mozilla.org/en-US/firefox/50.1.0/releasenotes/
https://www.mozilla.org/en-US/firefox/android/50.1.0/releasenotes/
https://www.mozilla.org/en-US/security/known-vulnerabilities/firefox/#firefox50.1
Mozilla Foundation Security Advisory 2016-94