CVE-2020-3517

What it is

A vulnerability in the Cisco Fabric Services component of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated attacker to cause process crashes, which could result in a denial of service (DoS) condition on an affected device. The attack vector is configuration dependent and could be remote or adjacent. For more information about the attack vector, see the Details section of this advisory. The vulnerability is due to insufficient error handling when the affected software parses Cisco Fabric Services messages. An attacker could exploit this vulnerability by sending malicious Cisco Fabric Services messages to an affected device. A successful exploit could allow the attacker to cause a reload of an affected device, which could result in a DoS condition.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

1.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2020-08-27 16:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:18 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.4% in the next 30 days (EPSS).
• Severity: 8.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2020-08-27 16:15 UTC

Last modified

2026-06-17 03:18 UTC

Exploit probability

1.4% · EPSS, next 30 days

Weakness

CWE-476 · NULL pointer dereference

Record status

Undergoing Analysis

Affected

• Cisco Firepower Extensible Operating System < 1.1.4.179
• Cisco Firepower Extensible Operating System < 2.0.1.153
• Cisco Firepower Extensible Operating System < 2.1.1.86
• Cisco Firepower Extensible Operating System < 2.2.1.70
• Cisco nx-os 6.0\(2\)a3\(1\)
• Cisco nx-os 6.0\(2\)a3\(2\)
• Cisco nx-os 6.0\(2\)a3\(4\)
• Cisco nx-os 6.0\(2\)a4\(1\)

Attack profile CVSS 3.1 · 8.6

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-3517.md and follow it. Check whether this project is affected by CVE-2020-3517. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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