A buffer size validation vulnerability in the overlayd service of Juniper Networks Junos OS may allow an unauthenticated remote attacker to send specially crafted packets to the device, triggering a partial Denial of Service (DoS) condition, or leading to remote code execution (RCE). Continued receipt and processing of these packets will sustain the partial DoS. The overlayd daemon handles Overlay OAM packets, such as ping and traceroute, sent to the overlay. The service runs as root by default and listens for UDP connections on port 4789. This issue results from improper buffer size validation, which can lead to a buffer overflow. Unauthenticated attackers can send specially crafted packets to trigger this vulnerability, resulting in possible remote code execution. overlayd runs by default in MX Series, ACX Series, and QFX Series platforms. The SRX Series does not support VXLAN and is therefore not vulnerable to this issue. Other platforms are also vulnerable if a Virtual Extensible LAN (VXLAN) overlay network is configured. This issue affects Juniper Networks Junos OS: 15.1 versions prior to 15.1R7-S9; 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S13, 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R2-S8, 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S7; 19.1 versions prior to 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R2-S4, 19.4R3-S1; 20.1 versions prior to 20.1R2-S1, 20.1R3; 20.2 versions prior to 20.2R2, 20.2R2-S1, 20.2R3; 20.3 versions prior to 20.3R1-S1.
| Software | From | Fixed in |
|---|---|---|
| juniper / junos | 15.1-r7 | 15.1-r7.x |
| juniper / junos | 15.1-f1 | 15.1-f1.x |
| juniper / junos | 15.1-f6-s4 | 15.1-f6-s4.x |
| juniper / junos | 15.1-f2-s3 | 15.1-f2-s3.x |
| juniper / junos | 15.1-f7 | 15.1-f7.x |
| juniper / junos | 15.1-r3 | 15.1-r3.x |
| juniper / junos | 15.1-r | 15.1-r.x |
| juniper / junos | 15.1-f2-s2 | 15.1-f2-s2.x |
| juniper / junos | 15.1-r6 | 15.1-r6.x |
| juniper / junos | 15.1-f4 | 15.1-f4.x |
| juniper / junos | 15.1-r4 | 15.1-r4.x |
| juniper / junos | 15.1-f2-s4 | 15.1-f2-s4.x |
| juniper / junos | 15.1-f5-s7 | 15.1-f5-s7.x |
| juniper / junos | 15.1-f6-s7 | 15.1-f6-s7.x |
| juniper / junos | 15.1-f6 | 15.1-f6.x |
| juniper / junos | 15.1-f2 | 15.1-f2.x |
| juniper / junos | 15.1-a1 | 15.1-a1.x |
| juniper / junos | 15.1-f3 | 15.1-f3.x |
| juniper / junos | 15.1-r2 | 15.1-r2.x |
| juniper / junos | 15.1-r4-s7 | 15.1-r4-s7.x |
| juniper / junos | 15.1-r4-s8 | 15.1-r4-s8.x |
| juniper / junos | 15.1-r5-s5 | 15.1-r5-s5.x |
| juniper / junos | 15.1-r6-s1 | 15.1-r6-s1.x |
| juniper / junos | 15.1-r5 | 15.1-r5.x |
| juniper / junos | 15.1-r1 | 15.1-r1.x |
| juniper / junos | 15.1-f2-s1 | 15.1-f2-s1.x |
| juniper / junos | 15.1-r5-s1 | 15.1-r5-s1.x |
| juniper / junos | 15.1-f5 | 15.1-f5.x |
| juniper / junos | 15.1-f6-s8 | 15.1-f6-s8.x |
| juniper / junos | 15.1-r5-s3 | 15.1-r5-s3.x |
| juniper / junos | 17.3-r1 | 17.3-r1.x |
| juniper / junos | 15.1-r5-s6 | 15.1-r5-s6.x |
| juniper / junos | 15.1-r6-s2 | 15.1-r6-s2.x |
| juniper / junos | 15.1-r6-s3 | 15.1-r6-s3.x |
| juniper / junos | 15.1-r6-s4 | 15.1-r6-s4.x |
| juniper / junos | 15.1-f6-s9 | 15.1-f6-s9.x |
| juniper / junos | 15.1-r4-s9 | 15.1-r4-s9.x |
| juniper / junos | 15.1-r6-s6 | 15.1-r6-s6.x |
| juniper / junos | 17.3-r2 | 17.3-r2.x |
| juniper / junos | 17.4-r1 | 17.4-r1.x |
| juniper / junos | 17.4-r2 | 17.4-r2.x |
| juniper / junos | 15.1-f | 15.1-f.x |
| juniper / junos | 17.3-r2-s2 | 17.3-r2-s2.x |
| juniper / junos | 17.3-r3 | 17.3-r3.x |
| juniper / junos | 18.1-r1 | 18.1-r1.x |
| juniper / junos | 15.1-f6-s3 | 15.1-f6-s3.x |
| juniper / junos | 18.1-r3 | 18.1-r3.x |
| juniper / junos | 15.1-r7-s1 | 15.1-r7-s1.x |
| juniper / junos | 15.1-f6-s10 | 15.1-f6-s10.x |
| juniper / junos | 17.3-r1-s4 | 17.3-r1-s4.x |
| juniper / junos | 17.4-r1-s3 | 17.4-r1-s3.x |
| juniper / junos | 18.1-r2 | 18.1-r2.x |
| juniper / junos | 18.2-r1 | 18.2-r1.x |
| juniper / junos | 15.1-r7-s2 | 15.1-r7-s2.x |
| juniper / junos | 15.1-r7-s3 | 15.1-r7-s3.x |
| juniper / junos | 17.4-r2-s2 | 17.4-r2-s2.x |
| juniper / junos | 17.4-r1-s1 | 17.4-r1-s1.x |
| juniper / junos | 18.2 | 18.2.x |
| juniper / junos | 18.2-r2-s1 | 18.2-r2-s1.x |
| juniper / junos | 18.2-r2-s2 | 18.2-r2-s2.x |
| juniper / junos | 18.2-r1-s3 | 18.2-r1-s3.x |
| juniper / junos | 18.3-r1-s1 | 18.3-r1-s1.x |
| juniper / junos | 17.3-r3-s1 | 17.3-r3-s1.x |
| juniper / junos | 17.3-r3-s2 | 17.3-r3-s2.x |
| juniper / junos | 17.4-r1-s2 | 17.4-r1-s2.x |
| juniper / junos | 17.3-r2-s1 | 17.3-r2-s1.x |
| juniper / junos | 18.3-r2 | 18.3-r2.x |
| juniper / junos | 18.3-r1 | 18.3-r1.x |
| juniper / junos | 17.4-r3 | 17.4-r3.x |
| juniper / junos | 17.4-r2-s1 | 17.4-r2-s1.x |
| juniper / junos | 18.1-r2-s2 | 18.1-r2-s2.x |
| juniper / junos | 15.1-f6-s2 | 15.1-f6-s2.x |
| juniper / junos | 15.1-f6-s1 | 15.1-f6-s1.x |
| juniper / junos | 15.1-f6-s5 | 15.1-f6-s5.x |
| juniper / junos | 15.1-f6-s6 | 15.1-f6-s6.x |
| juniper / junos | 18.4-r1 | 18.4-r1.x |
| juniper / junos | 17.4 | 17.4.x |
| juniper / junos | 18.1-r3-s4 | 18.1-r3-s4.x |
| juniper / junos | 18.1-r3-s3 | 18.1-r3-s3.x |
| juniper / junos | 18.1-r3-s2 | 18.1-r3-s2.x |
| juniper / junos | 18.1 | 18.1.x |
| juniper / junos | 18.1-r2-s1 | 18.1-r2-s1.x |
| juniper / junos | 18.1-r2-s4 | 18.1-r2-s4.x |
| juniper / junos | 15.1 | 15.1.x |
| juniper / junos | 17.3 | 17.3.x |
| juniper / junos | 18.3-r1-s2 | 18.3-r1-s2.x |
| juniper / junos | 18.3 | 18.3.x |
| juniper / junos | 18.4 | 18.4.x |
| juniper / junos | 17.4-r1-s5 | 17.4-r1-s5.x |
| juniper / junos | 18.1-r3-s1 | 18.1-r3-s1.x |
| juniper / junos | 17.3-r3-s3 | 17.3-r3-s3.x |
| juniper / junos | 17.4-r1-s7 | 17.4-r1-s7.x |
| juniper / junos | 17.4-r1-s4 | 17.4-r1-s4.x |
| juniper / junos | 18.4-r1-s1 | 18.4-r1-s1.x |
| juniper / junos | 17.3-r3-s4 | 17.3-r3-s4.x |
| juniper / junos | 17.3-r3-s5 | 17.3-r3-s5.x |
| juniper / junos | 17.4-r2-s3 | 17.4-r2-s3.x |
| juniper / junos | 17.4-r2-s4 | 17.4-r2-s4.x |
| juniper / junos | 17.4-r1-s6 | 17.4-r1-s6.x |
| juniper / junos | 18.1-r3-s5 | 18.1-r3-s5.x |
| juniper / junos | 18.3-r1-s3 | 18.3-r1-s3.x |
| juniper / junos | 18.2-r2-s3 | 18.2-r2-s3.x |
| juniper / junos | 18.2-r2-s4 | 18.2-r2-s4.x |
| juniper / junos | 18.3-r1-s4 | 18.3-r1-s4.x |
| juniper / junos | 18.2-r1-s4 | 18.2-r1-s4.x |
| juniper / junos | 18.2-r1-s5 | 18.2-r1-s5.x |
| juniper / junos | 18.2-r2 | 18.2-r2.x |
| juniper / junos | 17.3-r3-s6 | 17.3-r3-s6.x |
| juniper / junos | 18.4-r1-s3 | 18.4-r1-s3.x |
| juniper / junos | 18.4-r1-s4 | 18.4-r1-s4.x |
| juniper / junos | 18.4-r1-s2 | 18.4-r1-s2.x |
| juniper / junos | 19.1-r1 | 19.1-r1.x |
| juniper / junos | 19.1 | 19.1.x |
| juniper / junos | 17.3-r2-s3 | 17.3-r2-s3.x |
| juniper / junos | 17.4-r2-s5 | 17.4-r2-s5.x |
| juniper / junos | 17.4-r2-s6 | 17.4-r2-s6.x |
| juniper / junos | 17.4-r2-s7 | 17.4-r2-s7.x |
| juniper / junos | 19.2-r1 | 19.2-r1.x |
| juniper / junos | 18.4-r2 | 18.4-r2.x |
| juniper / junos | 18.2-r3 | 18.2-r3.x |
| juniper / junos | 18.1-r3-s6 | 18.1-r3-s6.x |
| juniper / junos | 18.1-r3-s7 | 18.1-r3-s7.x |
| juniper / junos | 19.1-r1-s1 | 19.1-r1-s1.x |
| juniper / junos | 19.1-r1-s3 | 19.1-r1-s3.x |
| juniper / junos | 19.1-r1-s2 | 19.1-r1-s2.x |
| juniper / junos | 15.1-r7-s4 | 15.1-r7-s4.x |
| juniper / junos | 17.3-r1-s1 | 17.3-r1-s1.x |
| juniper / junos | 15.1-r7-s5 | 15.1-r7-s5.x |
| juniper / junos | 18.2-r2-s5 | 18.2-r2-s5.x |
| juniper / junos | 18.2-r2-s6 | 18.2-r2-s6.x |
| juniper / junos | 18.4-r1-s5 | 18.4-r1-s5.x |
| juniper / junos | 15.1-f6-s12 | 15.1-f6-s12.x |
| juniper / junos | 19.2-r1-s1 | 19.2-r1-s1.x |
| juniper / junos | 19.2-r1-s2 | 19.2-r1-s2.x |
| juniper / junos | 18.3-r1-s5 | 18.3-r1-s5.x |
| juniper / junos | 18.2-r3-s1 | 18.2-r3-s1.x |
| juniper / junos | 17.3-r2-s4 | 17.3-r2-s4.x |
| juniper / junos | 18.3-r2-s1 | 18.3-r2-s1.x |
| juniper / junos | 18.3-r2-s2 | 18.3-r2-s2.x |
| juniper / junos | 17.4-r2-s8 | 17.4-r2-s8.x |
| juniper / junos | 18.4-r2-s1 | 18.4-r2-s1.x |
| juniper / junos | 19.3 | 19.3.x |
| juniper / junos | 19.3-r1 | 19.3-r1.x |
| juniper / junos | 19.2 | 19.2.x |
| juniper / junos | 18.4-r2-s2 | 18.4-r2-s2.x |
| juniper / junos | 18.3-r1-s6 | 18.3-r1-s6.x |
| juniper / junos | 18.2-r3-s2 | 18.2-r3-s2.x |
| juniper / junos | 18.1-r3-s8 | 18.1-r3-s8.x |
| juniper / junos | 19.2-r1-s3 | 19.2-r1-s3.x |
| juniper / junos | 18.3-r3 | 18.3-r3.x |
| juniper / junos | 19.4-r1 | 19.4-r1.x |
| juniper / junos | 19.3-r2 | 19.3-r2.x |
| juniper / junos | 19.1-r2 | 19.1-r2.x |
| juniper / junos | 18.4-r3 | 18.4-r3.x |
| juniper / junos | 18.4-r2-s3 | 18.4-r2-s3.x |
| juniper / junos | 18.3-r3-s1 | 18.3-r3-s1.x |
| juniper / junos | 18.1-r3-s9 | 18.1-r3-s9.x |
| juniper / junos | 17.3-r3-s7 | 17.3-r3-s7.x |
| juniper / junos | 19.3-r2-s1 | 19.3-r2-s1.x |
| juniper / junos | 19.3-r1-s1 | 19.3-r1-s1.x |
| juniper / junos | 19.2-r1-s4 | 19.2-r1-s4.x |
| juniper / junos | 20.1-r1 | 20.1-r1.x |
| juniper / junos | 19.4-r1-s1 | 19.4-r1-s1.x |
| juniper / junos | 19.3-r2-s2 | 19.3-r2-s2.x |
| juniper / junos | 19.1-r1-s4 | 19.1-r1-s4.x |
| juniper / junos | 18.4-r1-s6 | 18.4-r1-s6.x |
| juniper / junos | 18.3-r2-s3 | 18.3-r2-s3.x |
| juniper / junos | 18.2-r3-s3 | 18.2-r3-s3.x |
| juniper / junos | 17.4-r3-s1 | 17.4-r3-s1.x |
| juniper / junos | 17.4-r2-s9 | 17.4-r2-s9.x |
| juniper / junos | 17.4-r2-s10 | 17.4-r2-s10.x |
| juniper / junos | 15.1-r7-s7 | 15.1-r7-s7.x |
| juniper / junos | 18.2-r3-s4 | 18.2-r3-s4.x |
| juniper / junos | 17.3-r2-s5 | 17.3-r2-s5.x |
| juniper / junos | 18.4-r3-s2 | 18.4-r3-s2.x |
| juniper / junos | 18.4-r3-s1 | 18.4-r3-s1.x |
| juniper / junos | 18.4-r2-s4 | 18.4-r2-s4.x |
| juniper / junos | 19.1-r2-s1 | 19.1-r2-s1.x |
| juniper / junos | 19.1-r3 | 19.1-r3.x |
| juniper / junos | 19.1-r3-s1 | 19.1-r3-s1.x |
| juniper / junos | 15.1-r7-s6 | 15.1-r7-s6.x |
| juniper / junos | 19.4-r1-s2 | 19.4-r1-s2.x |
| juniper / junos | 20.1-r1-s1 | 20.1-r1-s1.x |
| juniper / junos | 17.4-r3-s2 | 17.4-r3-s2.x |
| juniper / junos | 17.4-r3-s3 | 17.4-r3-s3.x |
| juniper / junos | 20.2-r1 | 20.2-r1.x |
| juniper / junos | 20.1-r1-s2 | 20.1-r1-s2.x |
| juniper / junos | 20.1-r1-s3 | 20.1-r1-s3.x |
| juniper / junos | 19.4-r2 | 19.4-r2.x |
| juniper / junos | 19.4-r2-s1 | 19.4-r2-s1.x |
| juniper / junos | 19.3-r2-s3 | 19.3-r2-s3.x |
| juniper / junos | 19.1-r3-s2 | 19.1-r3-s2.x |
| juniper / junos | 18.4-r3-s3 | 18.4-r3-s3.x |
| juniper / junos | 18.4-r3-s4 | 18.4-r3-s4.x |
| juniper / junos | 18.2-r3-s5 | 18.2-r3-s5.x |
| juniper / junos | 18.1-r3-s10 | 18.1-r3-s10.x |
| juniper / junos | 18.3-r3-s2 | 18.3-r3-s2.x |
| juniper / junos | 19.2-r2 | 19.2-r2.x |
| juniper / junos | 17.3-r3-s8 | 17.3-r3-s8.x |
| juniper / junos | 17.4-r2-s11 | 17.4-r2-s11.x |
| juniper / junos | 18.3-r2-s4 | 18.3-r2-s4.x |
| juniper / junos | 19.3-r2-s4 | 19.3-r2-s4.x |
| juniper / junos | 18.3-r3-s3 | 18.3-r3-s3.x |
| juniper / junos | 20.2-r1-s1 | 20.2-r1-s1.x |
| juniper / junos | 20.2-r1-s2 | 20.2-r1-s2.x |
| juniper / junos | 19.4-r2-s2 | 19.4-r2-s2.x |
| juniper / junos | 19.2-r3 | 19.2-r3.x |
| juniper / junos | 18.4-r3-s5 | 18.4-r3-s5.x |
| juniper / junos | 19.4-r3 | 19.4-r3.x |
| juniper / junos | 19.3-r2-s5 | 19.3-r2-s5.x |
| juniper / junos | 19.3-r3 | 19.3-r3.x |
| juniper / junos | 19.2-r1-s5 | 19.2-r1-s5.x |
| juniper / junos | 19.1-r3-s3 | 19.1-r3-s3.x |
| juniper / junos | 18.4-r2-s5 | 18.4-r2-s5.x |
| juniper / junos | 18.4-r2-s6 | 18.4-r2-s6.x |
| juniper / junos | 17.3-r3-s9 | 17.3-r3-s9.x |
| juniper / junos | 17.3-r3-s10 | 17.3-r3-s10.x |
| juniper / junos | 15.1-r7-s8 | 15.1-r7-s8.x |
| juniper / junos | 19.1-r1-s5 | 19.1-r1-s5.x |
| juniper / junos | 18.4-r1-s7 | 18.4-r1-s7.x |
| juniper / junos | 20.3-r1 | 20.3-r1.x |
| juniper / junos | 18.2-r2-s7 | 18.2-r2-s7.x |
| juniper / junos | 18.1-r3-s11 | 18.1-r3-s11.x |
| juniper / junos | 19.2-r2-s1 | 19.2-r2-s1.x |
| juniper / junos | 18.2-r3-s6 | 18.2-r3-s6.x |
| juniper / junos | 18.2-r1-s2 | 18.2-r1-s2.x |
| juniper / junos | 20.1-r1-s4 | 20.1-r1-s4.x |
| juniper / junos | 18.4-r3-s6 | 18.4-r3-s6.x |
| juniper / junos | 20.2-r1-s3 | 20.2-r1-s3.x |
| juniper / junos | 19.2-r3-s1 | 19.2-r3-s1.x |
| juniper / junos | 17.4-r2-s12 | 17.4-r2-s12.x |
| juniper / junos | 19.4-r2-s3 | 19.4-r2-s3.x |
| juniper / junos | 20.2-r2 | 20.2-r2.x |
| juniper / junos | 20.1-r2 | 20.1-r2.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.