Vulnerability Database

346,508

Total vulnerabilities in the database

CVE-2021-0286 — juniper / junos_os_evolved

Improper Check for Unusual or Exceptional Conditions

A vulnerability in the handling of exceptional conditions in Juniper Networks Junos OS Evolved (EVO) allows an attacker to send specially crafted packets to the device, causing the Advanced Forwarding Toolkit manager (evo-aftmand-bt or evo-aftmand-zx) process to crash and restart, impacting all traffic going through the FPC, resulting in a Denial of Service (DoS). Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition. Following messages will be logged prior to the crash: Feb 2 10:14:39 fpc0 evo-aftmand-bt[16263]: [Error] Nexthop: Failed to get fwd nexthop for nexthop:32710470974358 label:1089551617 for session:18 probe:35 Feb 2 10:14:39 fpc0 evo-aftmand-bt[16263]: [Error] Nexthop: Failed to get fwd nexthop for nexthop:19241453497049 label:1089551617 for session:18 probe:37 Feb 2 10:14:39 fpc0 evo-aftmand-bt[16263]: [Error] Nexthop: Failed to get fwd nexthop for nexthop:19241453497049 label:1089551617 for session:18 probe:44 Feb 2 10:14:39 fpc0 evo-aftmand-bt[16263]: [Error] Nexthop: Failed to get fwd nexthop for nexthop:32710470974358 label:1089551617 for session:18 probe:47 Feb 2 10:14:39 fpc0 audit[16263]: ANOM_ABEND auid=4294967295 uid=0 gid=0 ses=4294967295 pid=16263 comm="EvoAftManBt-mai" exe="/usr/sbin/evo-aftmand-bt" sig=11 Feb 2 10:14:39 fpc0 kernel: audit: type=1701 audit(1612260879.272:17): auid=4294967295 uid=0 gid=0 ses=4294967295 pid=16263 comm="EvoAftManBt-mai" exe="/usr/sbin/evo-aftmand-bt" sig=1 This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R2-EVO; 21.1 versions prior to 21.1R2-EVO.

  • Published: Jul 15, 2021
  • Updated: Nov 16, 2025
  • CVE: CVE-2021-0286
  • Severity: High
  • Exploit:

CVSS v3:

  • Severity: High
  • Score: 7.5
  • AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v2:

  • Severity: High
  • Score: 7.8
  • AV:N/AC:L/Au:N/C:N/I:N/A:C

Frequently Asked Questions

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.