The (1) mdare64_48.sys, (2) mdare32_48.sys, (3) mdare32_52.sys, (4) mdare64_52.sys, and (5) Fortishield.sys drivers in Fortinet FortiClient before 5.2.4 do not properly restrict access to the API for management of processes and the Windows registry, which allows local users to obtain a privileged handle to a PID and possibly have unspecified other impact, as demonstrated by a 0x2220c8 ioctl call.

The Fortishield.sys driver in Fortinet FortiClient before 5.2.4 allows local users to execute arbitrary code with kernel privileges by setting the callback function in a (1) 0x220024 or (2) 0x220028 ioctl call.

The (1) mdare64_48.sys, (2) mdare32_48.sys, (3) mdare32_52.sys, and (4) mdare64_52.sys drivers in Fortinet FortiClient before 5.2.4 allow local users to write to arbitrary memory locations via a 0x226108 ioctl call.

The (1) mdare64_48.sys, (2) mdare32_48.sys, (3) mdare32_52.sys, and (4) mdare64_52.sys drivers in Fortinet FortiClient before 5.2.4 allow local users to read arbitrary kernel memory via a 0x22608C ioctl call.

FortiClient before 4.3.5.472 on Windows, before 4.0.3.134 on Mac OS X, and before 4.0 on Android; FortiClient Lite before 4.3.4.461 on Windows; FortiClient Lite 2.0 through 2.0.0223 on Android; and FortiClient SSL VPN before 4.0.2258 on Linux proceed with an SSL session after determining that the server's X.509 certificate is invalid, which allows man-in-the-middle attackers to obtain sensitive information by leveraging a password transmission that occurs before the user warning about the certificate problem.