I think - please correct me if I'm wrong - that Ada has pretty much the same problems as C if you use manual dynamic memory management. Ada supports Garbage Collection in theory, but it is optional, and I don't think many implementations actually supply a GC. Especially since Ada apparently is often used in realtime systems where dynamic memory management is usually avoided altogether (there is a subset of Ada specifically designed for building realtime software that explicitly prohibits any dynamic memory management).
Ada is - as far as I remember - much safer with regards to buffer overflows and bounds checking. But the bigger problem is probably that far more developers know C than Ada, and that something like an SSL library intended for widespread use needs to work with many different compilers and linkers. If you use GCC, I think it is possible to compile Ada code using the GNU Ada compiler and link it to C code compiled using the GNU C compiler, but I am not sure how things look if you use some other C compiler.
