A vulnerability due to the improper handling of direct memory access (DMA) buffers on EX4300 switches on Juniper Networks Junos OS allows an attacker sending specific unicast frames to trigger a Denial of Service (DoS) condition by exhausting DMA buffers, causing the FPC to crash and the device to restart. The DMA buffer leak is seen when receiving these specific, valid unicast frames on an interface without Layer 2 Protocol Tunneling (L2PT) or dot1x configured. Interfaces with either L2PT or dot1x configured are not vulnerable to this issue. When this issue occurs, DMA buffer usage keeps increasing and the following error log messages may be observed: Apr 14 14:29:34.360 /kernel: pid 64476 (pfex_junos), uid 0: exited on signal 11 (core dumped) Apr 14 14:29:33.790 init: pfe-manager (PID 64476) terminated by signal number 11. Core dumped! The DMA buffers on the FPC can be monitored by the executing vty command 'show heap': ID Base Total(b) Free(b) Used(b) % Name -- ---------- ----------- ----------- ----------- --- ----------- 0 4a46000 268435456 238230496 30204960 11 Kernel 1 18a46000 67108864 17618536 49490328 73 Bcm_sdk 2 23737000 117440512 18414552 99025960 84 DMA buf <<<<< keeps increasing 3 2a737000 16777216 16777216 0 0 DMA desc This issue affects Juniper Networks Junos OS on the EX4300: 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 19.1R1-S6, 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R2-S3, 19.4R3-S1; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2-S1, 20.2R3; 20.3 versions prior to 20.3R1-S1, 20.3R2.
| Software | From | Fixed in |
|---|---|---|
| juniper / junos | 17.3-r1 | 17.3-r1.x |
| juniper / junos | 17.3-r2 | 17.3-r2.x |
| juniper / junos | 17.3-r2-s2 | 17.3-r2-s2.x |
| juniper / junos | 17.3-r3 | 17.3-r3.x |
| juniper / junos | 17.3-r1-s4 | 17.3-r1-s4.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 | 17.3-r2-s1 | 17.3-r2-s1.x |
| juniper / junos | 17.3 | 17.3.x |
| juniper / junos | 17.3-r3-s3 | 17.3-r3-s3.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 | 17.3-r3-s6 | 17.3-r3-s6.x |
| juniper / junos | 17.3-r2-s3 | 17.3-r2-s3.x |
| juniper / junos | 17.3-r1-s1 | 17.3-r1-s1.x |
| juniper / junos | 17.3-r2-s4 | 17.3-r2-s4.x |
| juniper / junos | 17.3-r3-s7 | 17.3-r3-s7.x |
| juniper / junos | 17.3-r2-s5 | 17.3-r2-s5.x |
| juniper / junos | 17.3-r3-s8 | 17.3-r3-s8.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 | 17.4-r2-s12 | 17.4-r2-s12.x |
| juniper / junos | 17.4-r2-s11 | 17.4-r2-s11.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 | 17.4-r3-s2 | 17.4-r3-s2.x |
| juniper / junos | 17.4-r3-s3 | 17.4-r3-s3.x |
| juniper / junos | 17.4-r2-s8 | 17.4-r2-s8.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 | 17.4-r1-s7 | 17.4-r1-s7.x |
| juniper / junos | 17.4-r1-s4 | 17.4-r1-s4.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 | 17.4-r1-s5 | 17.4-r1-s5.x |
| juniper / junos | 17.4 | 17.4.x |
| juniper / junos | 17.4-r1-s2 | 17.4-r1-s2.x |
| juniper / junos | 17.4-r3 | 17.4-r3.x |
| juniper / junos | 17.4-r2-s1 | 17.4-r2-s1.x |
| juniper / junos | 17.4-r1-s3 | 17.4-r1-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 | 17.4-r1 | 17.4-r1.x |
| juniper / junos | 17.4-r2 | 17.4-r2.x |
| juniper / junos | 18.1-r1 | 18.1-r1.x |
| juniper / junos | 18.1-r3 | 18.1-r3.x |
| juniper / junos | 18.1-r2 | 18.1-r2.x |
| juniper / junos | 18.1-r2-s2 | 18.1-r2-s2.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 | 18.1-r3-s1 | 18.1-r3-s1.x |
| juniper / junos | 18.1-r3-s5 | 18.1-r3-s5.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 | 18.1-r3-s8 | 18.1-r3-s8.x |
| juniper / junos | 18.1-r3-s9 | 18.1-r3-s9.x |
| juniper / junos | 18.1-r3-s10 | 18.1-r3-s10.x |
| juniper / junos | 18.1-r3-s11 | 18.1-r3-s11.x |
| juniper / junos | 18.2-r2-s7 | 18.2-r2-s7.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 | 18.2-r3-s5 | 18.2-r3-s5.x |
| juniper / junos | 18.2-r3-s4 | 18.2-r3-s4.x |
| juniper / junos | 18.2-r3-s3 | 18.2-r3-s3.x |
| juniper / junos | 18.2-r3-s2 | 18.2-r3-s2.x |
| juniper / junos | 18.2-r3-s1 | 18.2-r3-s1.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 | 18.2-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 | 18.2-r3 | 18.2-r3.x |
| juniper / junos | 18.2-r1 | 18.2-r1.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 | 18.2 | 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 | 18.3-r1-s2 | 18.3-r1-s2.x |
| juniper / junos | 18.3 | 18.3.x |
| juniper / junos | 18.3-r2 | 18.3-r2.x |
| juniper / junos | 18.3-r1 | 18.3-r1.x |
| juniper / junos | 18.3-r1-s4 | 18.3-r1-s4.x |
| juniper / junos | 18.3-r1-s3 | 18.3-r1-s3.x |
| juniper / junos | 18.3-r1-s5 | 18.3-r1-s5.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 | 18.3-r1-s6 | 18.3-r1-s6.x |
| juniper / junos | 18.3-r3 | 18.3-r3.x |
| juniper / junos | 18.3-r2-s3 | 18.3-r2-s3.x |
| juniper / junos | 18.3-r3-s1 | 18.3-r3-s1.x |
| juniper / junos | 18.3-r3-s3 | 18.3-r3-s3.x |
| juniper / junos | 18.3-r2-s4 | 18.3-r2-s4.x |
| juniper / junos | 18.3-r3-s2 | 18.3-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 | 18.4-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 | 18.4-r3 | 18.4-r3.x |
| juniper / junos | 18.4-r2-s3 | 18.4-r2-s3.x |
| juniper / junos | 18.4-r1-s6 | 18.4-r1-s6.x |
| juniper / junos | 18.4-r2-s2 | 18.4-r2-s2.x |
| juniper / junos | 18.4-r2-s1 | 18.4-r2-s1.x |
| juniper / junos | 18.4-r1-s1 | 18.4-r1-s1.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 | 18.4-r2 | 18.4-r2.x |
| juniper / junos | 18.4-r1-s5 | 18.4-r1-s5.x |
| juniper / junos | 18.4-r1 | 18.4-r1.x |
| juniper / junos | 18.4 | 18.4.x |
| juniper / junos | 18.4-r3-s6 | 18.4-r3-s6.x |
| juniper / junos | 18.4-r1-s7 | 18.4-r1-s7.x |
| juniper / junos | 18.4-r3-s5 | 18.4-r3-s5.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 | 19.1-r1-s5 | 19.1-r1-s5.x |
| juniper / junos | 19.1-r3-s3 | 19.1-r3-s3.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 | 19.1-r1 | 19.1-r1.x |
| juniper / junos | 19.1 | 19.1.x |
| juniper / junos | 19.1-r1-s4 | 19.1-r1-s4.x |
| juniper / junos | 19.1-r2 | 19.1-r2.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 | 19.1-r3-s2 | 19.1-r3-s2.x |
| juniper / junos | 19.2-r2 | 19.2-r2.x |
| juniper / junos | 19.2-r1-s4 | 19.2-r1-s4.x |
| juniper / junos | 19.2 | 19.2.x |
| juniper / junos | 19.2-r1-s3 | 19.2-r1-s3.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 | 19.2-r1 | 19.2-r1.x |
| juniper / junos | 19.2-r2-s1 | 19.2-r2-s1.x |
| juniper / junos | 19.2-r3 | 19.2-r3.x |
| juniper / junos | 19.2-r1-s5 | 19.2-r1-s5.x |
| juniper / junos | 19.2-r3-s1 | 19.2-r3-s1.x |
| juniper / junos | 19.3-r2-s5 | 19.3-r2-s5.x |
| juniper / junos | 19.3-r3 | 19.3-r3.x |
| juniper / junos | 19.3 | 19.3.x |
| juniper / junos | 19.3-r1 | 19.3-r1.x |
| juniper / junos | 19.3-r2-s2 | 19.3-r2-s2.x |
| juniper / junos | 19.3-r2 | 19.3-r2.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 | 19.3-r2-s3 | 19.3-r2-s3.x |
| juniper / junos | 19.3-r2-s4 | 19.3-r2-s4.x |
| juniper / junos | 19.4-r2-s2 | 19.4-r2-s2.x |
| juniper / junos | 19.4-r2 | 19.4-r2.x |
| juniper / junos | 19.4-r2-s1 | 19.4-r2-s1.x |
| juniper / junos | 19.4-r1-s2 | 19.4-r1-s2.x |
| juniper / junos | 19.4-r1-s1 | 19.4-r1-s1.x |
| juniper / junos | 19.4-r1 | 19.4-r1.x |
| juniper / junos | 19.4-r3 | 19.4-r3.x |
| juniper / junos | 20.1-r1-s4 | 20.1-r1-s4.x |
| juniper / junos | 20.1-r1 | 20.1-r1.x |
| juniper / junos | 20.1-r1-s1 | 20.1-r1-s1.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 | 20.2-r1 | 20.2-r1.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 | 20.2-r1-s3 | 20.2-r1-s3.x |
| juniper / junos | 20.2-r2 | 20.2-r2.x |
| juniper / junos | 20.3-r1 | 20.3-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.