# CVE-2019-1718: Cisco Identity Services Engine SSL Renegotiation Denial of Service Vulnerability

> Unauthenticated remote attackers can cause denial of service in Cisco ISE by flooding SSL renegotiation requests, leading to high CPU usage.

- **Severity:** Medium 5.3 (`CVSS:3.0/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Apr 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-x3m5-7cfg-xfpq

## What is CVE-2019-1718?

CVE-2019-1718 is a medium-severity denial of service vulnerability in Cisco Identity Services Engine, published on 17 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the web interface of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to trigger high CPU usage, resulting in a denial of service (DoS) condition. The vulnerability is due to improper handling of Secure Sockets Layer (SSL) renegotiation requests. An attacker could exploit this vulnerability by sending renegotiation requests at a high rate. An successful exploit could increase the resource usage on the system, eventually leading to a DoS condition. This vulnerability affects version 2.1.

Weakness: CWE-399

## Which versions are affected by CVE-2019-1718?

It affects 1 product.


Products: Cisco Identity Services Engine.

## How do I fix CVE-2019-1718?

No fix has been published for CVE-2019-1718 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1718 being exploited?

There is no known exploitation of CVE-2019-1718 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-2019-1718 and fix it if it is affected.

What it is: CVE-2019-1718 is a medium-severity denial of service vulnerability in Cisco Identity Services Engine, published on 17 Apr 2019. 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-2019-1718 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-2019-1718/ (Markdown: https://insights.sbomify.com/CVE-2019-1718/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1718
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1718
- OSV: https://osv.dev/vulnerability/CVE-2019-1718

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-1718/
Summaries are generated and may contain mistakes; the official description above is the record.