Firstly, upvote cx42net's answer, because as he says, the vulnerability only affects a certain type of package - the statically linked one.
The difference between static and dynamic linking is the use of shared objects. In a statically linked program, all 3rd party code is "baked in". If there are any vulnerabilities in it, the whole lot needs updating to fix that library.
By contrast, dynamically linked programs use shared libs which can be updated independently (e.g. by your distribution) and thus fixes in third party libraries are handled by your distribution as soon as possible, and apply to all software run post update (because running applications will have the old SOs mapped into memory).
How do you tell which you have? The unix
file command will tell you:
$ file /usr/bin/skype
ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV),
dynamically linked (uses shared libs), for GNU/Linux 2.6.9, stripped
If you see that, you're okay. It is highly unlikely you're using the static version from a debian repository - that just wouldn't make sense from a distribution point of view (the whole point of using static linking is to get around incompatible shared libraries - whereas if you have a repository, you can set dependencies on compatible libraries and kernel versions and make the download smaller to boot).
noticed some crashes of the skype client and think that there could have been attacks on the vulnerabilities.
I'd be more inclined to put that down to the beta status of the software - although you're right to be cautious and investigating your system will not hurt.