An improper certificate validation vulnerability [CWE-295] in FortiClientWindows 6.4 all versions, 7.0.0 through 7.0.7, FortiClientMac 6.4 all versions, 7.0 all versions, 7.2.0 through 7.2.4, FortiClientLinux 6.4 all versions, 7.0 all versions, 7.2.0 through 7.2.4, FortiClientAndroid 6.4 all versions, 7.0 all versions, 7.2.0 and FortiClientiOS 5.6 all versions, 6.0.0 through 6.0.1, 7.0.0 through 7.0.6 SAML SSO feature may allow an unauthenticated attacker to man-in-the-middle the communication between the FortiClient and  both the service provider and the identity provider.