# CVE-2021-1594: Cisco Identity Services Engine Privilege Escalation Vulnerability

> An attacker in a man-in-the-middle position can inject commands into Cisco ISE API endpoints to execute arbitrary code with root privileges.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 6 Oct 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-8rx9-j5hq-fx8v

## What is CVE-2021-1594?

CVE-2021-1594 is a high-severity command injection vulnerability in Cisco Identity Services Engine, published on 6 Oct 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A vulnerability in the REST API of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to perform a command injection attack and elevate privileges to root. This vulnerability is due to insufficient input validation for specific API endpoints. An attacker in a man-in-the-middle position could exploit this vulnerability by intercepting and modifying specific internode communications from one ISE persona to another ISE persona. A successful exploit could allow the attacker to run arbitrary commands with root privileges on the underlying operating system. To exploit this vulnerability, the attacker would need to decrypt HTTPS traffic between two ISE personas that are located on separate nodes.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-266 (Incorrect Privilege Assignment)

## Which versions are affected by CVE-2021-1594?

It affects 1 product.


Products: Cisco Identity Services Engine.

## How do I fix CVE-2021-1594?

No fix has been published for CVE-2021-1594 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1594 being exploited?

There is no known exploitation of CVE-2021-1594 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-2021-1594 and fix it if it is affected.

What it is: CVE-2021-1594 is a high-severity command injection vulnerability in Cisco Identity Services Engine, published on 6 Oct 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-1594 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-2021-1594/ (Markdown: https://insights.sbomify.com/CVE-2021-1594/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1594
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1594
- OSV: https://osv.dev/vulnerability/CVE-2021-1594

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1594/
Summaries are generated and may contain mistakes; the official description above is the record.