Mantis before 1.1.0a2 does not implement per-item access control for Issue History (Bug History), which allows remote attackers to obtain sensitive information by reading the Change column, as demonstrated by the Change column of a custom field.
Exploitability
AV:NAC:LAu:NImpact
C:PI:NA:N5/AV:N/AC:L/Au:N/C:P/I:N/A:N