# CVE-2022-20756: Cisco Identity Services Engine RADIUS Service Denial of Service Vulnerability

> Unauthenticated remote attackers can cause Cisco ISE to stop processing RADIUS requests, denying legitimate access until a manual restart.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Apr 2022
- **Updated:** 6 Nov 2024
- **Also known as:** GHSA-qwcc-f7fm-5q6x

## What is CVE-2022-20756?

CVE-2022-20756 is a high-severity denial of service vulnerability in Cisco Identity Services Engine, published on 6 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the RADIUS feature of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause the affected system to stop processing RADIUS packets. This vulnerability is due to improper handling of certain RADIUS requests. An attacker could exploit this vulnerability by attempting to authenticate to a network or a service where the access server is using Cisco ISE as the RADIUS server. A successful exploit could allow the attacker to cause Cisco ISE to stop processing RADIUS requests, causing authentication/authorization timeouts, which would then result in legitimate requests being denied access. Note: To recover the ability to process RADIUS packets, a manual restart of the affected Policy Service Node (PSN) is required. See the Details section for more information.

Weakness: CWE-399

## Which versions are affected by CVE-2022-20756?

It affects 1 product.


Products: Cisco Identity Services Engine.

## How do I fix CVE-2022-20756?

No fix has been published for CVE-2022-20756 yet. Limit exposure of the affected software until one is available.

## Is CVE-2022-20756 being exploited?

There is no known exploitation of CVE-2022-20756 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-2022-20756 and fix it if it is affected.

What it is: CVE-2022-20756 is a high-severity denial of service vulnerability in Cisco Identity Services Engine, published on 6 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2022-20756 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-2022-20756/ (Markdown: https://insights.sbomify.com/CVE-2022-20756/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-20756
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-20756
- OSV: https://osv.dev/vulnerability/CVE-2022-20756

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-20756/
Summaries are generated and may contain mistakes; the official description above is the record.