A new security vulnerability (CVE-2022-20959) has been identified in the External RESTful Services (ERS) API of Cisco Identity Services Engine (ISE) Software, which could potentially allow a remote attacker to perform a cross-site scripting (XSS) attack against a user of the interface of an affected device. The vulnerability stems from insufficient input validation. In this post, we'll dive into the details of the vulnerability, including its background, the code snippet, and ways to mitigate the risk.

Vulnerability Details

Cisco Identity Services Engine (ISE) is a network administration product that enables the creation and enforcement of security and access policies for endpoint devices connected to a company's routers and switches. The External RESTful Services (ERS) API provides programmatic access to ISE features, such as managing users, devices, and security groups.

The core issue behind CVE-2022-20959 relates to insufficient input validation in the ERS API. An attacker could exploit this vulnerability by persuading an authenticated administrator of the web-based management interface to click a malicious link.

A successful exploit would grant the attacker the ability to execute arbitrary script code in the context of the affected interface, potentially leading to unauthorized access to sensitive information, such as browser history and stored credentials.

Code Snippet

The following sample script demonstrates an example of a malicious link that could exploit this vulnerability:

<a href="https://vulnerable-ise.example.com/admin/path?variable=<script>malicious_code_here();</script>">;
  Click me for important information!

In this example, if an authenticated ISE administrator clicks on the link, the malicious script would execute within the context of their active ISE session.

You can find more information about this vulnerability from the following sources

1. Cisco Security Advisory - CVE-2022-20959 - Cisco Identity Services Engine (ISE) Cross-Site Scripting Vulnerability
2. CVE Details - CVE-2022-20959 Detail

Exploit Mitigation

To protect against this vulnerability, it is essential to ensure that your Cisco ISE deployment is patched with the latest updates and security fixes. Cisco has already released software updates that address this vulnerability, which can be found in the Cisco Security Advisory.

Additionally, it is recommended to follow best security practices, such as enforcing strong access controls and promoting security awareness among the administrators responsible for managing the Cisco ISE web interface. It is crucial to educate staff about the risks associated with clicking on suspicious or unexpected links, even when they originate from seemingly trusted sources.


CVE-2022-20959 is a significant vulnerability in Cisco Identity Services Engine (ISE) Software that could have severe implications if left unaddressed. By updating the affected software, adhering to best security practices, and fostering a culture of security awareness, organizations can substantially minimize the risk of being compromised by an attacker exploiting this vulnerability.


Published on: 10/26/2022 15:15:00 UTC
Last modified on: 10/28/2022 17:40:00 UTC