On Juniper Networks EX and QFX Series, an authentication bypass vulnerability may allow a user connected to the console port to login as root without any password. This issue might only occur in certain scenarios: • At the first reboot after performing device factory reset using the command “request system zeroize”; or • A temporary moment during the first reboot after the software upgrade when the device configured in Virtual Chassis mode. This issue affects Juniper Networks Junos OS on EX and QFX Series: 14.1X53 versions prior to 14.1X53-D53; 15.1 versions prior to 15.1R7-S4; 15.1X53 versions prior to 15.1X53-D593; 16.1 versions prior to 16.1R7-S4; 17.1 versions prior to 17.1R2-S11, 17.1R3-S1; 17.2 versions prior to 17.2R3-S3; 17.3 versions prior to 17.3R2-S5, 17.3R3-S6; 17.4 versions prior to 17.4R2-S9, 17.4R3; 18.1 versions prior to 18.1R3-S8; 18.2 versions prior to 18.2R2; 18.3 versions prior to 18.3R1-S7, 18.3R2. This issue does not affect Juniper Networks Junos OS 12.3.