Vulnerability Database

346,508

Total vulnerabilities in the database

CVE-2023-36839 — juniper / junos

Improper Validation of Specified Quantity in Input

An Improper Validation of Specified Quantity in Input vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker who sends specific LLDP packets to cause a Denial of Service(DoS).

This issue occurs when specific LLDP packets are received and telemetry polling is being done on the device. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected.

This issue affects:

Juniper Networks Junos OS

  • All versions prior to 20.4R3-S8;
  • 21.1 version 21.1R1 and later versions;
  • 21.2 versions prior to 21.2R3-S5;
  • 21.3 versions prior to 21.3R3-S4;
  • 21.4 versions prior to 21.4R3-S3;
  • 22.1 versions prior to 22.1R3-S2;
  • 22.2 versions prior to 22.2R3;
  • 22.3 versions prior to 22.3R2-S2;
  • 22.4 versions prior to 22.4R2;

Juniper Networks Junos OS Evolved

  • All versions prior to 20.4R3-S8-EVO;
  • 21.1 version 21.1R1-EVO and later versions;
  • 21.2 versions prior to 21.2R3-S5-EVO;
  • 21.3 versions prior to 21.3R3-S4-EVO;
  • 21.4 versions prior to 21.4R3-S3-EVO;
  • 22.1 versions prior to 22.1R3-S2-EVO;
  • 22.2 versions prior to 22.2R3-EVO;
  • 22.3 versions prior to 22.3R2-S2-EVO;
  • 22.4 versions prior to 22.4R1-S1-EVO;
  • Published: Oct 12, 2023
  • Updated: Nov 16, 2025
  • CVE: CVE-2023-36839
  • Severity: Medium
  • Exploit:

CVSS v3:

  • Severity: Medium
  • Score: 6.5
  • AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Software From Fixed in
juniper / junos 20.4-r1 20.4-r1.x
juniper / junos 20.4-r1-s1 20.4-r1-s1.x
juniper / junos 21.1-r1 21.1-r1.x
juniper / junos 20.4-r2 20.4-r2.x
juniper / junos 21.2-r1 21.2-r1.x
juniper / junos 20.4-r2-s1 20.4-r2-s1.x
juniper / junos 21.1-r1-s1 21.1-r1-s1.x
juniper / junos 21.2-r1-s1 21.2-r1-s1.x
juniper / junos 21.1-r2 21.1-r2.x
juniper / junos 20.4-r3 20.4-r3.x
juniper / junos 21.3-r1 21.3-r1.x
juniper / junos 21.3-r2 21.3-r2.x
juniper / junos 21.2-r2 21.2-r2.x
juniper / junos 20.4-r3-s1 20.4-r3-s1.x
juniper / junos 20.4-r2-s2 20.4-r2-s2.x
juniper / junos 21.1-r3 21.1-r3.x
juniper / junos 21.1-r2-s1 21.1-r2-s1.x
juniper / junos 21.2 21.2.x
juniper / junos 20.4 20.4.x
juniper / junos 21.1-r2-s2 21.1-r2-s2.x
juniper / junos 21.2-r1-s2 21.2-r1-s2.x
juniper / junos 21.2-r2-s1 21.2-r2-s1.x
juniper / junos 21.2-r2-s2 21.2-r2-s2.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 20.4-r3-s2 20.4-r3-s2.x
juniper / junos 21.1-r3-s1 21.1-r3-s1.x
juniper / junos 21.2-r3 21.2-r3.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 20.4-r3-s3 20.4-r3-s3.x
juniper / junos 21.4 21.4.x
juniper / junos 21.3 21.3.x
juniper / junos 21.1-r3-s2 21.1-r3-s2.x
juniper / junos 22.1-r1-s1 22.1-r1-s1.x
juniper / junos 22.1-r2 22.1-r2.x
juniper / junos 21.4-r3 21.4-r3.x
juniper / junos 22.1-r1-s2 22.1-r1-s2.x
juniper / junos 22.1-r2-s2 22.1-r2-s2.x
juniper / junos 21.4-r2-s2 21.4-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 20.4-r3-s4 20.4-r3-s4.x
juniper / junos 21.2-r3-s2 21.2-r3-s2.x
juniper / junos 21.2-r3-s1 21.2-r3-s1.x
juniper / junos 22.3-r1 22.3-r1.x
juniper / junos 21.1-r3-s3 21.1-r3-s3.x
juniper / junos 22.2-r2 22.2-r2.x
juniper / junos 22.1-r3-s1 22.1-r3-s1.x
juniper / junos 21.1-r3-s4 21.1-r3-s4.x
juniper / junos 21.3-r3-s2 21.3-r3-s2.x
juniper / junos 22.3-r2 22.3-r2.x
juniper / junos 22.1-r3 22.1-r3.x
juniper / junos 20.4-r3-s5 20.4-r3-s5.x
juniper / junos 22.2-r1-s2 22.2-r1-s2.x
juniper / junos - 20.4
juniper / junos 21.4-r3-s1 21.4-r3-s1.x
juniper / junos 22.2-r2-s1 22.2-r2-s1.x
juniper / junos 22.1-r2-s1 22.1-r2-s1.x
juniper / junos 21.2-r3-s3 21.2-r3-s3.x
juniper / junos 21.3-r3-s3 21.3-r3-s3.x
juniper / junos 21.4-r3-s2 21.4-r3-s2.x
juniper / junos 20.4-r3-s6 20.4-r3-s6.x
juniper / junos 22.3-r1-s1 22.3-r1-s1.x
juniper / junos 22.4-r1 22.4-r1.x
juniper / junos 22.2-r2-s2 22.2-r2-s2.x
juniper / junos 22.3-r1-s2 22.3-r1-s2.x
juniper / junos 22.4-r1-s1 22.4-r1-s1.x
juniper / junos 22.4-r1-s2 22.4-r1-s2.x
juniper / junos 20.4-r3-s7 20.4-r3-s7.x
juniper / junos 21.1-r3-s5 21.1-r3-s5.x
juniper / junos 21.2-r3-s4 21.2-r3-s4.x
juniper / junos 22.3-r2-s1 22.3-r2-s1.x
juniper / junos_os_evolved 20.4-r1 20.4-r1.x
juniper / junos_os_evolved 21.1-r1 21.1-r1.x
juniper / junos_os_evolved 21.1-r2 21.1-r2.x
juniper / junos_os_evolved 21.1-r1-s1 21.1-r1-s1.x
juniper / junos_os_evolved 21.2-r1 21.2-r1.x
juniper / junos_os_evolved 21.2-r1-s1 21.2-r1-s1.x
juniper / junos_os_evolved 21.2-r2 21.2-r2.x
juniper / junos_os_evolved 20.4-r1-s1 20.4-r1-s1.x
juniper / junos_os_evolved 20.4-r1-s2 20.4-r1-s2.x
juniper / junos_os_evolved 20.4-r2 20.4-r2.x
juniper / junos_os_evolved 20.4-r2-s1 20.4-r2-s1.x
juniper / junos_os_evolved 20.4-r2-s2 20.4-r2-s2.x
juniper / junos_os_evolved 20.4-r2-s3 20.4-r2-s3.x
juniper / junos_os_evolved 20.4-r3 20.4-r3.x
juniper / junos_os_evolved 20.4-r3-s1 20.4-r3-s1.x
juniper / junos_os_evolved 21.3-r1 21.3-r1.x
juniper / junos_os_evolved 20.4 20.4.x
juniper / junos_os_evolved 21.2 21.2.x
juniper / junos_os_evolved 21.2-r1-s2 21.2-r1-s2.x
juniper / junos_os_evolved 21.2-r2-s1 21.2-r2-s1.x
juniper / junos_os_evolved 21.3-r1-s1 21.3-r1-s1.x
juniper / junos_os_evolved - 20.4
juniper / junos_os_evolved 20.4-r3-s2 20.4-r3-s2.x
juniper / junos_os_evolved 21.4-r1 21.4-r1.x
juniper / junos_os_evolved 21.4-r1-s1 21.4-r1-s1.x
juniper / junos_os_evolved 21.2-r2-s2 21.2-r2-s2.x
juniper / junos_os_evolved 21.1-r3 21.1-r3.x
juniper / junos_os_evolved 21.2-r3 21.2-r3.x
juniper / junos_os_evolved 21.3-r2 21.3-r2.x
juniper / junos_os_evolved 21.3 21.3.x
juniper / junos_os_evolved 21.4 21.4.x
juniper / junos_os_evolved 21.1-r3-s1 21.1-r3-s1.x
juniper / junos_os_evolved 20.4-r3-s4 20.4-r3-s4.x
juniper / junos_os_evolved 20.4-r3-s3 20.4-r3-s3.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 21.4-r2 21.4-r2.x
juniper / junos_os_evolved 21.4-r2-s1 21.4-r2-s1.x
juniper / junos_os_evolved 21.4-r2-s2 21.4-r2-s2.x
juniper / junos_os_evolved 22.1-r1-s1 22.1-r1-s1.x
juniper / junos_os_evolved 22.1-r1-s2 22.1-r1-s2.x
juniper / junos_os_evolved 21.4-r1-s2 21.4-r1-s2.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
juniper / junos_os_evolved 21.2-r3-s1 21.2-r3-s1.x
juniper / junos_os_evolved 21.3-r3 21.3-r3.x
juniper / junos_os_evolved 20.4-r3-s5 20.4-r3-s5.x
juniper / junos_os_evolved 22.3-r1 22.3-r1.x
juniper / junos_os_evolved 22.1-r2 22.1-r2.x
juniper / junos_os_evolved 21.4-r3 21.4-r3.x
juniper / junos_os_evolved 22.2-r2 22.2-r2.x
juniper / junos_os_evolved 21.2-r3-s2 21.2-r3-s2.x
juniper / junos_os_evolved 21.2-r3-s3 21.2-r3-s3.x
juniper / junos_os_evolved 21.1-r3-s2 21.1-r3-s2.x
juniper / junos_os_evolved 21.1-r3-s3 21.1-r3-s3.x
juniper / junos_os_evolved 21.2-r3-s4 21.2-r3-s4.x
juniper / junos_os_evolved 21.4-r3-s1 21.4-r3-s1.x
juniper / junos_os_evolved 21.4-r3-s2 21.4-r3-s2.x
juniper / junos_os_evolved 20.4-r3-s6 20.4-r3-s6.x
juniper / junos_os_evolved 22.2-r2-s1 22.2-r2-s1.x
juniper / junos_os_evolved 21.3-r3-s1 21.3-r3-s1.x
juniper / junos_os_evolved 21.3-r3-s2 21.3-r3-s2.x
juniper / junos_os_evolved 21.3-r3-s3 21.3-r3-s3.x
juniper / junos_os_evolved 22.1-r2-s1 22.1-r2-s1.x
juniper / junos_os_evolved 22.1-r3 22.1-r3.x
juniper / junos_os_evolved 20.4-r3-s7 20.4-r3-s7.x
juniper / junos_os_evolved 22.1-r3-s1 22.1-r3-s1.x
juniper / junos_os_evolved 22.2-r2-s2 22.2-r2-s2.x
juniper / junos_os_evolved 22.3-r1-s1 22.3-r1-s1.x
juniper / junos_os_evolved 22.3-r1-s2 22.3-r1-s2.x
juniper / junos_os_evolved 22.3-r2 22.3-r2.x
juniper / junos_os_evolved 22.4-r1 22.4-r1.x
juniper / junos_os_evolved 22.3-r2-s1 22.3-r2-s1.x

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.