I am able to reproduce this with the latest version of mongod on github (2.5.3-pre-) as well as 2.4.5 (must be compiled with SSL). # This is how I compiled mongodb scons --ssl all 1. Start up a mongod without any of the options specified on the docs ./mongod # no command-line opts 2. Start up a mongo shell without any of the options given in the above documentation. ./mongo # no command line opts 3. Follow these instructions for adding an x509 subject as a user $ mongo --version MongoDB shell version: 2.4.5 $ mongo > db.addUser({ user:"CN=client,OU=kerneluser,O=10Gen,L=New York City,ST=New York,C=US", roles:["readAnyDatabase","readWriteAnyDatabase"], userSource:"$external" }); # or $ mongo --version MongoDB shell version: 2.5.3-pre- $ mongo > db.addUser({ user:"CN=client,OU=kerneluser,O=10Gen,L=New York City,ST=New York,C=US", pwd:"anypwd", roles:["readWrite","dbAdmin"] }) 4. Follow these instructions for attempting to authenticate with a certificate > db.getSiblingDB("$external").auth({ mechanism:"MONGODB-X509", user:"CN=client,OU=kerneluser,O=10Gen,L=New York City,ST=New York,C=US" }); The mongo shell will crash after the 4th step