An Incorrect Permission Assignment vulnerability in shell processing of Juniper Networks Junos OS Evolved allows a low-privileged local user to modify the contents of a configuration file which could cause another user to execute arbitrary commands within the context of the follow-on user’s session. If the follow-on user is a high-privileged administrator, the attacker could leverage this vulnerability to take complete control of the target system. While this issue is triggered by a user, other than the attacker, accessing the Junos shell, an attacker simply requires Junos CLI access to exploit this vulnerability. This issue affects Juniper Networks Junos OS Evolved: 20.4-EVO versions prior to 20.4R3-S1-EVO; All versions of 21.1-EVO; 21.2-EVO versions prior to 21.2R3-EVO; 21.3-EVO versions prior to 21.3R2-EVO. This issue does not affect Juniper Networks Junos OS Evolved versions prior to 19.2R1-EVO.