Wasn't heartbleed a fairly typical buffer overflow?
> [...] OpenSSL adds a wrapper around malloc & free so that the library will cache memory on it's own, and not free it to the protective malloc. [...] So then a bug shows up which leaks the content of memory mishandled by that layer. [...]
> OpenSSL is not developed by a responsible team.
Heartbleed is reading beyond the intended bounds remotely. I don't think there were similar attacks before hand, but I could be wrong. I only have a base level knowledge here.