The Meeting Server in IBM Sametime 8.x through 8.5.2.1 and 9.x through 9.0.0.1 allows remote attackers to cause a denial of service (room unusability) by generating a large number of fictitious users to enter a meeting room.
Improper Input Validation 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.