# CVE-2017-6653: Denial of service in Cisco Identity Services Engine

> Unauthenticated remote attackers can cause a denial of service on Cisco ISE GUI by sending high-rate TCP connections due to insufficient rate limiting.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/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:** 22 May 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-px76-ghcx-4p3m

## What is CVE-2017-6653?

CVE-2017-6653 is a high-severity denial of service vulnerability in Cisco Identity Services Engine, published on 22 May 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the TCP throttling process for the GUI of the Cisco Identity Services Engine (ISE) 2.1(0.474) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device where the ISE GUI may fail to respond to new or established connection requests. The vulnerability is due to insufficient TCP rate limiting protection on the GUI. An attacker could exploit this vulnerability by sending the affected device a high rate of TCP connections to the GUI. An exploit could allow the attacker to cause the GUI to stop responding while the high rate of connections is in progress. Cisco Bug IDs: CSCvc81803.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-399

## Which versions are affected by CVE-2017-6653?

It affects 1 product.


Products: Cisco Identity Services Engine.

## How do I fix CVE-2017-6653?

No fix has been published for CVE-2017-6653 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-6653 being exploited?

There is no known exploitation of CVE-2017-6653 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-2017-6653 and fix it if it is affected.

What it is: CVE-2017-6653 is a high-severity denial of service vulnerability in Cisco Identity Services Engine, published on 22 May 2017. 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-2017-6653 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-2017-6653/ (Markdown: https://insights.sbomify.com/CVE-2017-6653/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-6653
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-6653
- OSV: https://osv.dev/vulnerability/CVE-2017-6653

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From sbomify Insights: https://insights.sbomify.com/CVE-2017-6653/
Summaries are generated and may contain mistakes; the official description above is the record.