If REST API is enabled, the Junos OS login credentials are vulnerable to brute force attacks. The high default connection limit of the REST API may allow an attacker to brute-force passwords using advanced scripting techniques. Additionally, administrators who do not enforce a strong password policy can increase the likelihood of success from brute force attacks. Affected releases are Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D49; 15.1 versions prior to 15.1F6-S12, 15.1R7-S3; 15.1X49 versions prior to 15.1X49-D160; 15.1X53 versions prior to 15.1X53-D236, 15.1X53-D495, 15.1X53-D591, 15.1X53-D69; 16.1 versions prior to 16.1R3-S10, 16.1R4-S12, 16.1R6-S6, 16.1R7-S3; 16.1X65 versions prior to 16.1X65-D49; 16.2 versions prior to 16.2R2-S7; 17.1 versions prior to 17.1R2-S10, 17.1R3; 17.2 versions prior to 17.2R1-S8, 17.2R3-S1; 17.3 versions prior to 17.3R3-S2; 17.4 versions prior to 17.4R1-S6, 17.4R2-S2; 18.1 versions prior to 18.1R2-S4, 18.1R3-S1; 18.2 versions prior to 18.2R1-S5; 18.2X75 versions prior to 18.2X75-D30; 18.3 versions prior to 18.3R1-S1.

When configuring a stateless firewall filter in Junos OS, terms named using the format "internal-n" (e.g. "internal-1", "internal-2", etc.) are silently ignored. No warning is issued during configuration, and the config is committed without error, but the filter criteria will match all packets leading to unexpected results. Affected releases are Juniper Networks Junos OS: All versions prior to and including 12.3; 14.1X53 versions prior to 14.1X53-D130, 14.1X53-D49; 15.1 versions prior to 15.1F6-S12, 15.1R7-S4; 15.1X49 versions prior to 15.1X49-D161, 15.1X49-D170; 15.1X53 versions prior to 15.1X53-D236, 15.1X53-D496, 15.1X53-D69; 16.1 versions prior to 16.1R7-S4, 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, 17.2R3-S1; 17.3 versions prior to 17.3R3-S4; 17.4 versions prior to 17.4R1-S7, 17.4R2-S3; 18.1 versions prior to 18.1R2-S4, 18.1R3-S4; 18.2 versions prior to 18.2R1-S5, 18.2R2-S1; 18.2X75 versions prior to 18.2X75-D40; 18.3 versions prior to 18.3R1-S3; 18.4 versions prior to 18.4R1-S1, 18.4R1-S2.

Memory leak in Juniper JUNOS Packet Forwarding Engine (PFE) allows remote attackers to cause a denial of service (memory exhaustion and device reboot) via certain IPv6 packets.

TCP, when using a large Window Size, makes it easier for remote attackers to guess sequence numbers and cause a denial of service (connection loss) to persistent TCP connections by repeatedly injecting a TCP RST packet, especially in protocols that use long-lived connections, such as BGP.