The sys_recvfrom function in nmbd in Samba 3.6.x before 3.6.24, 4.0.x before 4.0.19, and 4.1.x before 4.1.9 allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via a malformed UDP packet.
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.