A session fixation vulnerability in J-Web on Junos OS may allow an attacker to use social engineering techniques to fix and hijack a J-Web administrators web session and potentially gain administrative access to the device. This issue affects: Juniper Networks Junos OS 12.3 versions prior to 12.3R12-S15 on EX Series; 12.3X48 versions prior to 12.3X48-D85 on SRX Series; 14.1X53 versions prior to 14.1X53-D51; 15.1 versions prior to 15.1F6-S13, 15.1R7-S5; 15.1X49 versions prior to 15.1X49-D180 on SRX Series; 15.1X53 versions prior to 15.1X53-D238; 16.1 versions prior to 16.1R4-S13, 16.1R7-S5; 16.2 versions prior to 16.2R2-S10; 17.1 versions prior to 17.1R3-S1; 17.2 versions prior to 17.2R2-S8, 17.2R3-S3; 17.3 versions prior to 17.3R3-S5; 17.4 versions prior to 17.4R2-S8, 17.4R3; 18.1 versions prior to 18.1R3-S8; 18.2 versions prior to 18.2R3; 18.3 versions prior to 18.3R3; 18.4 versions prior to 18.4R2; 19.1 versions prior to 19.1R1-S2, 19.1R2.