SOMETIMES, YOU CAN JUST FEEL THE SECURITY IN THE DESIGN (JUNIPER JUNOS EVOLVED CVE-2026-21902 PRE-AUTH RCE)

Summary from the TLDR InfoSec newsletter

CVE-2026-21902 (CVSS 9.8) is a pre-authentication RCE in Juniper Junos OS Evolved on PTX Series routers caused by the On-Box Anomaly Detection Framework's Python REST API binding to 0.0.0.0:8160 instead of an internal-only interface, exposing unauthenticated shell command execution running as root. Exploitation requires four unauthenticated HTTP POST requests: register a RE-SHELL command, wrap it in a DAG, schedule a DAG instance, then commit, after which the schedule enforcer passes the attacker-controlled syntax field directly into subprocess.run(). Affected versions are Junos OS Evolved 25.4 before 25.4R1-S1-EVO and 25.4R2-EVO. Operators should patch immediately and audit exposure of port 8160/TCP at network boundaries.