An issue in TheGreenBow Windows Standard VPN Client 6.87.108 (and older), Windows Enterprise VPN Client 6.87.109 (and older), Windows Enterprise VPN Client 7.5.007 (and older), Android VPN Client 6.4.5 (and older) VPN Client Linux 3.4 (and older), VPN Client MacOS 2.4.10 (and older) allows a remote attacker to execute arbitrary code via the IKEv2 Authentication phase, it accepts malformed ECDSA signatures and establishes the tunnel.