[HoLyVieR]

Not all crash bug can lead to remote code execution. A null dereference bug is a good example of that. No mater the context, you won't be able to do anything other than crash the software.

[mmozeiko]

That's not quite right. NULL pointer dereference can be exploited:

https://blogs.oracle.com/ksplice/entry/much_ado_about_null_e...

http://tk-blog.blogspot.com/2009/01/exploitable-userland-nul...