The CmdAuthenticate::authenticateX509 function in db/commands/authenticationcommands.cpp in mongod in MongoDB 2.6.x before 2.6.2 allows remote attackers to cause a denial of service (daemon crash) by attempting authentication with an invalid X.509 client certificate.

MongoDB before 2.4.13 and 2.6.x before 2.6.8 allows remote attackers to cause a denial of service via a crafted UTF-8 string in a BSON request.

It was reported that it is possible for remote unauthenticated attackers to cause the host to kill mongoDB service due to memory exhaustion. This issue can be triggered by making multiple database creation requests. Even if authentication fails, the requested database is created in memory. Eventually, the host runs out of memory and kills Mongo service resulting in a denial of service. After service restart, all created databases are deleted.

The issue was identified in versions 2.4 and 2.6. The issue was found to be not reproducible on 3.0.11 and 3.2.4.

External references: https://jira.mongodb.org/browse/SERVER-24378