# CVE-2025-20343: Cisco Identity Services Engine Radius Suppression Denial of Service Vulnerability

> An unauthenticated remote attacker can cause a denial of service by sending crafted RADIUS requests to Cisco ISE when a specific suppression setting is enabled.

- **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:** 5 Nov 2025
- **Updated:** 5 Nov 2025
- **Also known as:** GHSA-cfwq-p5hw-9v6p

## What is CVE-2025-20343?

CVE-2025-20343 is a high-severity denial of service vulnerability in Cisco Identity Services Engine, published on 5 Nov 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the RADIUS setting Reject RADIUS requests from clients with repeated failures on Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause Cisco ISE to restart unexpectedly.

This vulnerability is due to a logic error when processing a RADIUS access request for a MAC address that is already a rejected endpoint. An attacker could exploit this vulnerability by sending a specific sequence of multiple crafted RADIUS access request messages to Cisco ISE. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when Cisco ISE restarts.

Weakness: CWE-697 (Incorrect Comparison)

## Which versions are affected by CVE-2025-20343?

It affects 1 product.


Products: Cisco Identity Services Engine.

## How do I fix CVE-2025-20343?

No fix has been published for CVE-2025-20343 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-20343 being exploited?

There is no known exploitation of CVE-2025-20343 in the wild and no public exploit code.

Public exploit code:

- PoC y analisis de CVE-2025-20343: DoS remoto no autenticado en Cisco ISE via paquetes RADIUS. (github_poc): https://github.com/fevar54/Blackash-CVE-2025-20343

## 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-2025-20343 and fix it if it is affected.

What it is: CVE-2025-20343 is a high-severity denial of service vulnerability in Cisco Identity Services Engine, published on 5 Nov 2025. 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-2025-20343 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-2025-20343/ (Markdown: https://insights.sbomify.com/CVE-2025-20343/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-20343
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-20343
- OSV: https://osv.dev/vulnerability/CVE-2025-20343

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-20343/
Summaries are generated and may contain mistakes; the official description above is the record.