Due to the Improper Handling of an Unexpected Data Type in the processing of EVPN routes on Juniper Networks Junos OS and Junos OS Evolved, an attacker in direct control of a BGP client connected to a route reflector, or via a machine in the middle (MITM) attack, can send a specific EVPN route contained within a BGP Update, triggering a routing protocol daemon (RPD) crash, leading to a Denial of Service (DoS) condition. Continued receipt and processing of these specific EVPN routes could create a sustained Denial of Service (DoS) condition. This issue only occurs on BGP route reflectors, only within a BGP EVPN multicast environment, and only when one or more BGP clients have 'leave-sync-route-oldstyle' enabled. This issue affects: Juniper Networks Junos OS 21.3 versions prior to 21.3R3-S2; 21.4 versions prior to 21.4R2-S2, 21.4R3; 22.1 versions prior to 22.1R1-S2, 22.1R3; 22.2 versions prior to 22.2R2. Juniper Networks Junos OS Evolved 21.3 version 21.3R1-EVO and later versions prior to 21.4R3-EVO; 22.1 versions prior to 22.1R1-S2-EVO, 22.1R3-EVO; 22.2 versions prior to 22.2R2-EVO. This issue does not affect: Juniper Networks Junos OS versions prior to 21.3R1. Juniper Networks Junos OS Evolved versions prior to 21.3R1-EVO.
| Software | From | Fixed in |
|---|---|---|
| juniper / junos | 21.3-r1 | 21.3-r1.x |
| juniper / junos | 21.3-r2 | 21.3-r2.x |
| juniper / junos | 21.4-r1-s1 | 21.4-r1-s1.x |
| juniper / junos | 21.3-r1-s1 | 21.3-r1-s1.x |
| juniper / junos | 21.3-r1-s2 | 21.3-r1-s2.x |
| juniper / junos | 21.4-r1 | 21.4-r1.x |
| juniper / junos | 21.3-r2-s1 | 21.3-r2-s1.x |
| juniper / junos | 21.3-r2-s2 | 21.3-r2-s2.x |
| juniper / junos | 21.4-r1-s2 | 21.4-r1-s2.x |
| juniper / junos | 22.1-r1 | 22.1-r1.x |
| juniper / junos | 21.3-r3 | 21.3-r3.x |
| juniper / junos | 21.3-r3-s1 | 21.3-r3-s1.x |
| juniper / junos | 21.4-r2 | 21.4-r2.x |
| juniper / junos | 21.4-r2-s1 | 21.4-r2-s1.x |
| juniper / junos | 21.4 | 21.4.x |
| juniper / junos | 21.3 | 21.3.x |
| juniper / junos | 22.1-r1-s1 | 22.1-r1-s1.x |
| juniper / junos | 22.1-r2 | 22.1-r2.x |
| juniper / junos | 22.1-r2-s2 | 22.1-r2-s2.x |
| juniper / junos | 22.2-r1 | 22.2-r1.x |
| juniper / junos | 22.2-r1-s1 | 22.2-r1-s1.x |
| juniper / junos_os_evolved | 21.3-r1 | 21.3-r1.x |
| juniper / junos_os_evolved | 21.3-r1-s1 | 21.3-r1-s1.x |
| juniper / junos_os_evolved | 21.3-r2 | 21.3-r2.x |
| juniper / junos_os_evolved | 22.1-r1 | 22.1-r1.x |
| juniper / junos_os_evolved | 21.3-r2-s1 | 21.3-r2-s1.x |
| juniper / junos_os_evolved | 21.3-r2-s2 | 21.3-r2-s2.x |
| juniper / junos_os_evolved | 22.1-r1-s1 | 22.1-r1-s1.x |
| juniper / junos_os_evolved | 22.2-r1-s1 | 22.2-r1-s1.x |
| juniper / junos_os_evolved | 22.2-r1 | 22.2-r1.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.