The Ignite Realtime Smack XMPP API, as used in Atlassian Bamboo before 5.9.9 and 5.10.x before 5.10.0, allows remote configured XMPP servers to execute arbitrary Java code via serialized data in an XMPP message.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.