Fusion 5.0.4 and Heartbleed/OpenSSL vulnerability -- affected or not?

Hi all,

My Parallels Desktop imploded, forcing me to start from scratch, and I figured now is the perfect time to move (back) to Fusion, once and for all. One question for you guys (hopefully a simple one):

I see that Fusion 6.0.3 was released to protect against Heartbleed, but there is no corresponding patch for 5.0.4.

Does this mean that the vulnerability does not exist in earlier versions, or that it does exist and is simply not being patched for older versions? Finances are tight, and I was hoping to just use my existing 5.0.4 license.

Can I do so safely?

Thanks!