An Information Exposure vulnerability in J-Web of Juniper Networks Junos OS allows an unauthenticated attacker to elevate their privileges over the target system through opportunistic use of an authenticated users session. This issue affects: Juniper Networks Junos OS 12.3 versions prior to 12.3R12-S17; 17.3 versions prior to 17.3R3-S10; 17.4 versions prior to 17.4R2-S12 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R2-S4 18.3R3-S4; 18.4 versions prior to 18.4R2-S5 18.4R3-S5; 19.1 versions prior to 19.1R1-S6 19.1R2-S2 19.1R3-S3; 19.2 versions prior to 19.2R1-S5 19.2R3 19.2R3-S1; 19.3 versions prior to 19.3R2-S4 19.3R3; 19.4 versions prior to 19.4R1-S3 19.4R2-S2 19.4R3; 20.1 versions prior to 20.1R1-S4 20.1R2; 20.2 versions prior to 20.2R1-S1 20.2R2.