# CVE-2026-20352: Cisco Identity Services Engine RADIUS Denial of Service Vulnerability

> Unauthenticated remote attackers can cause a denial of service on Cisco ISE by sending crafted RADIUS requests, blocking network access for unauthenticated endpoints.

- **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:** 16 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-qwcp-547c-v9v8

## What is CVE-2026-20352?

CVE-2026-20352 is a high-severity denial of service vulnerability in Cisco Identity Services Engine Software, published on 16 Sep 2026. 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 a denial of service (DoS) condition on an affected device.

This vulnerability is due to improper handling of certain RADIUS requests. An attacker could exploit this vulnerability by sending a crafted RADIUS request directly to an affected device. A successful exploit could allow the attacker to cause the ISE node to become unavailable. For single node deployments in that condition, endpoints that have not already authenticated would be unable to access the network until the node comes back up on its own.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-20352?


## How do I fix CVE-2026-20352?

No fix has been published for CVE-2026-20352 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-20352 being exploited?

There is no known exploitation of CVE-2026-20352 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20352 and fix it if it is affected.

What it is: CVE-2026-20352 is a high-severity denial of service vulnerability in Cisco Identity Services Engine Software, published on 16 Sep 2026. 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-2026-20352 in the wild and no public exploit code.

Affected product: Cisco Identity Services Engine Software. 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-2026-20352/ (Markdown: https://insights.sbomify.com/CVE-2026-20352/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20352
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20352
- OSV: https://osv.dev/vulnerability/CVE-2026-20352

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-20352/
Summaries are generated and may contain mistakes; the official description above is the record.