You can't. Bitcoin transactions are final once confirmed.

Update your software.

How do you know that you were a victim of that vulnerability? Was your wallet encrypted? If so, you were not a victim of that vulnerability. Did you have your web browser open to random, unknown, and possibly malicious sites? If not, then you were not a victim of that vulnerability. Just because there was a vulnerability does not mean that you were automatically a victim of it. It is also possible you just have malware on your computer and that is stealing your money, in which case you will need to remove said malware.