The Ubuntu One Client for Ubuntu 10.04 LTS, 11.04, 11.10, and 12.04 LTS does not properly validate SSL certificates, which allows remote attackers to spoof a server and modify or read sensitive information via a man-in-the-middle (MITM) attack.
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.