CVE-2021-1594

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. High risk of data exposure, data tampering, service disruption.

Exploit odds

1.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-10-06 20:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:32 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.4% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-10-06 20:15 UTC

Last modified

2026-06-17 03:32 UTC

Exploit probability

1.4% · EPSS, next 30 days

Weakness

CWE-266

Record status

Modified

Affected

• Cisco Identity Services Engine < 2.6.0
• Cisco Identity Services Engine 2.4\(0.902\)
• Cisco Identity Services Engine 2.6\(0.156\)
• Cisco Identity Services Engine 2.6.0
• Cisco Identity Services Engine 2.7\(0.903\)
• Cisco Identity Services Engine 2.7.0
• Cisco Identity Services Engine 3.0\(0.458\)
• Cisco Identity Services Engine 3.0.0

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-1594.md and follow it. Check whether this project is affected by CVE-2021-1594. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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