Contact your SSH vendor for a fix if source code is not available. This is the patch for ssh-1.2.31 package. Compile the ssh package. This advisory has been released early due to the disclosure of information regarding the problem in public forums. The detection is done using a hash table that is dynamically allocated based on the size of the received packet.
Most modern systems implement the later behaviors and are thus vulnerable.
However, a small degree of knowledge in exploit code development would be needed to implement a working exploit. All the product names mentioned herein are trademarks of their respective owners.