bson/cbsonmodule.c in the mongo-python-driver (aka. pymongo) before 2.5.2, as used in MongoDB, allows context-dependent attackers to cause a denial of service (NULL pointer dereference and crash) via vectors related to decoding of an "invalid DBRef."

The find prototype in scripting/enginev8.h in MongoDB 2.4.0 through 2.4.4 allows remote authenticated users to cause a denial of service (uninitialized pointer dereference and server crash) or possibly execute arbitrary code via an invalid RefDB object.

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