CVE-2021-0263

CVE-2021-0263 is a data processing vulnerability in Juniper Networks Junos OS on PTX Series routers. Specifically, the Multi-Service process (multi-svcs) on the FPC can become unresponsive during heavy route churn when J-Flow is activated, leading to a Denial of Service (DoS) condition by affecting traffic forwarding. This vulnerability impacts various Junos OS versions across the PTX Series, including 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, and 20.3. The vulnerability has a CVSSv3.1 score of 5.9 (Medium), indicating a network-based attack with high impact on availability and high attack complexity. An unauthenticated attacker can exploit this without user interaction, leading to a complete loss of service. There is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage regarding this vulnerability. It is not listed in CISA's Known Exploited Vulnerabilities Catalog.