Dear blapat20,
It says in the solution section of the security advisory :
"The following software releases have been updated to resolve this specific issue: Junos OS 12.1X46-D45 (pending release), 12.1X47-D30, 12.3X48-D20, 15.1X49-D30 and all subsequent releases."
So JunOS 12.1X46-D45 still hasn't been released and that is why the JTAC download page hasn't been updated yet. If you're not using the RTSP ALG you can alternatively disable it using this command :
set security alg rtsp disable