Insufficient capability checks in a messaging web service made it possible to view other users' names and online status. Versions affected: 4.5 to 4.5.3, 4.4 to 4.4.7, 4.3 to 4.3.11, 4.1 to 4.1.17 and earlier unsupported versions. Versions fixed: 4.5.4, 4.4.8, 4.3.12 and 4.1.18