The IP Phone Personal Address Book (PAB) Synchronizer feature in Cisco Unified Communications Manager (aka CUCM, formerly CallManager) 4.1, 4.2 before 4.2(3)SR4b, 4.3 before 4.3(2)SR1b, 5.x before 5.1(3e), 6.x before 6.1(3), and 7.0 before 7.0(2) sends privileged directory-service account credentials to the client in cleartext, which allows remote attackers to modify the CUCM configuration and perform other privileged actions by intercepting these credentials, and then using them in requests unrelated to the intended synchronization task, as demonstrated by (1) DC Directory account credentials in CUCM 4.x and (2) TabSyncSysUser account credentials in CUCM 5.x through 7.x.

Per: http://www.cisco.com/en/US/products/products_security_advisory09186a0080a8643c.shtml

"Impact

Successful exploitation of this vulnerability may allow an attacker to intercept user credentials that allow the attacker to escalate their privilege level and obtain complete administrative access to a vulnerable Cisco Unified Communications Manager system. If integrated with an external directory service, the intercepted user credentials may allow an attacker to gain access to additional systems configured to use the directory service for authentication."