A persistent Cross-Site Scripting (XSS) vulnerability in Junos OS J-Web interface may allow remote unauthenticated attackers to perform administrative actions on the Junos device. Successful exploitation requires a Junos administrator to first perform certain diagnostic actions on J-Web. This issue affects: Juniper Networks Junos OS 12.1X46 versions prior to 12.1X46-D86; 12.3 versions prior to 12.3R12-S13; 12.3X48 versions prior to 12.3X48-D80; 14.1X53 versions prior to 14.1X53-D51; 15.1 versions prior to 15.1F6-S13, 15.1R7-S4; 15.1X49 versions prior to 15.1X49-D171, 15.1X49-D180; 15.1X53 versions prior to 15.1X53-D497, 15.1X53-D69; 16.1 versions prior to 16.1R7-S5; 16.2 versions prior to 16.2R2-S9; 17.1 versions prior to 17.1R3; 17.2 versions prior to 17.2R1-S8, 17.2R2-S7, 17.2R3-S1; 17.3 versions prior to 17.3R3-S6; 17.4 versions prior to 17.4R1-S7, 17.4R2-S4, 17.4R3; 18.1 versions prior to 18.1R3-S5; 18.2 versions prior to 18.2R1-S5, 18.2R2-S3, 18.2R3; 18.3 versions prior to 18.3R1-S3, 18.3R2, 18.3R3; 18.4 versions prior to 18.4R1-S2, 18.4R2.