Duo has identified and fixed an issue with the Duo Network Gateway (DNG) product in which some customer-provided SSL certificates and private keys were not excluded from logging. This issue resulted in certificate and private key information being written out in plain-text to local files on the DNG host. Any private keys logged in this way could be viewed by those with access to the DNG host operating system without any need for reversing encrypted values or similar techniques. An attacker that gained access to the DNG logs and with the ability to intercept and manipulate network traffic between a user and the DNG, could decrypt and manipulate SSL/TLS connections to the DNG and to the protected applications behind it. Duo Network Gateway (DNG) versions 1.3.3 through 1.5.7 are affected.