An Incorrect Default Permissions vulnerability in Juniper Networks Junos OS allows an unauthenticated attacker with local access to the device to create a backdoor with root privileges. The issue is caused by improper directory permissions on a certain system directory, allowing an attacker with access to this directory to create a backdoor with root privileges. This issue affects Juniper Networks Junos OS: All versions prior to 20.4R3-S5; 21.1 versions prior to 21.1R3-S4; 21.2 versions prior to 21.2R3-S4; 21.3 versions prior to 21.3R3-S3; * 21.4 versions prior to 21.4R3-S1.