Debraj Ray found that when under some circumstance the SaslAuthenticatorImpl's sasl_dispose() function will crash out at destruction. The incident seems to be random and only when certain authentication and encryption combinations are used during connection.
After digging a little deeper, I found that when BOOST communication error occurs, the shutdownSocket (eventually triggering sasl_dispose()) could be called from various threads resulting in a race condition of freeing the handle. This can be reproduced with the querysubmitter. This is reproducible since 1.12.0+.
Debraj Ray will be adding a patch to resolve this incident.