MongoDB before 2.0.9 and 2.2.x before 2.2.4 does not properly validate requests to the nativeHelper function in SpiderMonkey, which allows remote authenticated users to cause a denial of service (invalid memory access and server crash) or execute arbitrary code via a crafted memory address in the first argument.
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."