Apache Ignite serialization mechanism does not have a list of classes allowed for serialization/deserialization, which makes it possible to run arbitrary code when 3-rd party vulnerable classes are present in Ignite classpath. The vulnerability can be exploited if the one sends a specially prepared form of a serialized object to one of the deserialization endpoints of some Ignite components - discovery SPI, Ignite persistence, Memcached endpoint, socket steamer.

External References:

https://lists.apache.org/thread.html/45e7d5e2c6face85aab693f5ae0616563132ff757e5a558da80d0209@%3Cdev.ignite.apache.org%3E