> virtually every significant piece of C software has some sort of vulnerability in it

The GNU 'echo' program is pretty significant, in the sense it's installed widely, and used widely. What sort of vulnerability exists?

You don't get points for internet pedantry. Especially when it should be obvious that you're choosing to use a definition of "significant" that doesn't match what I was using in my comment.

virtually, adverb [ as submodifier ] nearly; almost: the disease destroyed virtually all the vineyards in Orange County | the college became virtually bankrupt.