Junos OS: authd allows assignment of IP address requested by DHCP subscriber logging in with Option 50 (Requested IP Address)

Summary

On MX Series and M120/M320 platforms configured in a Broadband Edge (BBE) environment, subscribers logging in with DHCP Option 50 to request a specific IP address will be assigned the requested IP address, even if there is a static MAC to IP address binding in the access profile. In the problem scenario, with a hardware-address and IP address configured under address-assignment pool, if a subscriber logging in with DHCP Option 50, the subscriber will not be assigned an available address from the matched pool, but will still get the requested IP address. A malicious DHCP subscriber may be able to utilize this vulnerability to create duplicate IP address assignments, leading to a denial of service for valid subscribers or unauthorized information disclosure via IP address assignment spoofing. Affected releases are Juniper Networks Junos OS: 15.1 versions prior to 15.1R7-S2, 15.1R8; 16.1 versions prior to 16.1R4-S12, 16.1R7-S2, 16.1R8; 16.2 versions prior to 16.2R2-S7, 16.2R3; 17.1 versions prior to 17.1R2-S9, 17.1R3; 17.2 versions prior to 17.2R1-S7, 17.2R2-S6, 17.2R3; 17.3 versions prior to 17.3R2-S4, 17.3R3; 17.4 versions prior to 17.4R2; 18.1 versions prior to 18.1R2-S3, 18.1R3.