# CVE-2023-20213: Denial of service in Cisco Identity Services Engine Software

> An unauthenticated adjacent attacker can crash the CDP process on Cisco ISE by sending crafted traffic, requiring manual restart to restore neighbor discovery.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Nov 2023
- **Updated:** 12 Jun 2025
- **Also known as:** GHSA-wrrj-56x5-rfqr

## What is CVE-2023-20213?

CVE-2023-20213 is a medium-severity denial of service vulnerability in Cisco Identity Services Engine, published on 1 Nov 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the CDP processing feature of Cisco ISE could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition of the CDP process on an affected device. This vulnerability is due to insufficient bounds checking when an affected device processes CDP traffic. An attacker could exploit this vulnerability by sending crafted CDP traffic to the device. A successful exploit could cause the CDP process to crash, impacting neighbor discovery and the ability of Cisco ISE to determine the reachability of remote devices. After a crash, the CDP process must be manually restarted using the cdp enable command in interface configuration mode.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2023-20213?

It affects 1 product.


Products: Cisco Identity Services Engine.

## How do I fix CVE-2023-20213?

No fix has been published for CVE-2023-20213 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-20213 being exploited?

There is no known exploitation of CVE-2023-20213 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Identity Services Engine

- [CVE-2026-76460](https://insights.sbomify.com/CVE-2026-76460/): Cisco Identity Services Engine Incorrect Use of Privileged APIs (critical 10.0, exploited in the wild)
- [CVE-2025-20337](https://insights.sbomify.com/CVE-2025-20337/): Cisco Identity Services Engine Injection (critical 10.0, exploited in the wild)
- [CVE-2025-20281](https://insights.sbomify.com/CVE-2025-20281/): Cisco Identity Services Engine Injection (critical 10.0, exploited in the wild)
- [CVE-2026-20130](https://insights.sbomify.com/CVE-2026-20130/): Cisco Identity Services Engine Hardening Release - Improper Neutralization Vulnerabilities (critical 10.0)
- [CVE-2026-20192](https://insights.sbomify.com/CVE-2026-20192/): Cisco Identity Services Engine Hardening Release - Access Control Vulnerabilities (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-20213 and fix it if it is affected.

What it is: CVE-2023-20213 is a medium-severity denial of service vulnerability in Cisco Identity Services Engine, published on 1 Nov 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-20213 in the wild and no public exploit code.

Affected product: Cisco Identity Services Engine. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-20213/ (Markdown: https://insights.sbomify.com/CVE-2023-20213/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-20213
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-20213
- OSV: https://osv.dev/vulnerability/CVE-2023-20213

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-20213/
Summaries are generated and may contain mistakes; the official description above is the record.