CVE-2023-20089
A vulnerability in the Link Layer Discovery Protocol (LLDP) feature for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) Mode could allow an unauthenticated, adjacent attacker to cause a memory leak, which could result in an unexpected reload of the device. This vulnerability is due to incorrect error checking when parsing ingress LLDP packets. An attacker could exploit this vulnerability by sending a steady stream of crafted LLDP packets to an affected device. A successful exploit could allow the attacker to cause a memory leak, which could result in a denial of service (DoS) condition when the device unexpectedly reloads. Note: This vulnerability cannot be exploited by transit traffic through the device. The crafted LLDP packet must be targeted to a directly connected interface, and the attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent). In addition, the attack surface for this vulnerability can be reduced by disabling LLDP on interfaces where it is not required.
| Software | From | Fixed in |
|---|---|---|
| cisco / nx-os | 15.2(1g) | 15.2(1g).x |
| cisco / nx-os | 15.2(2e) | 15.2(2e).x |
| cisco / nx-os | 15.2(2f) | 15.2(2f).x |
| cisco / nx-os | 15.2(2g) | 15.2(2g).x |
| cisco / nx-os | 15.2(2h) | 15.2(2h).x |
| cisco / nx-os | 15.2(3e) | 15.2(3e).x |
| cisco / nx-os | 15.2(3f) | 15.2(3f).x |
| cisco / nx-os | 15.2(3g) | 15.2(3g).x |
| cisco / nx-os | 15.2(4d) | 15.2(4d).x |
| cisco / nx-os | 15.2(4e) | 15.2(4e).x |
| cisco / nx-os | 15.2(4f) | 15.2(4f).x |
| cisco / nx-os | 15.2(5c) | 15.2(5c).x |
| cisco / nx-os | 15.2(5d) | 15.2(5d).x |
| cisco / nx-os | 15.2(5e) | 15.2(5e).x |
| cisco / nx-os | 16.0(1g) | 16.0(1g).x |
| cisco / nx-os | 16.0(1j) | 16.0(1j).x |
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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.