A fix has already been released. You can't always go by package version since fixes are backported to older versions.
Look: https://security-tracker.debian.org/tracker/CVE-2017-7494
I'm safe
# dpkg -l | grep samba
ii samba 2:4.2.14+dfsg-0+deb8u6 amd64 SMB/CIFS file, print, and login server for Unix