External risk intelligence

Cisco ISE Improper Neutralization Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 10.0)

CVE-2026-20130

Cisco Identity Services Engine (ISE) is an enterprise network administration and identity management product. It is commonly deployed as a centralized gateway for authentication and policy enforcement, often serving as a critical edge service for network access control (NAC), making its management and service interfaces frequently accessible within the broader enterprise network infrastructure.

Cisco Identity Services Engine

3.1.0 to before 3.3.03.3.03.4.03.5.0

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in Cisco Identity Services Engine and its Passive Identity Connector, stemming from improper handling of special characters in software. This issue could allow for significant compromise of confidentiality, integrity, and availability within affected systems. The main concern at this stage is confirming relevance and exposure across the environment.

Flaw affects identity and network access control software.
Remember for its potential to disrupt core network services.
Confirm if your Cisco Identity Services Engine is exposed.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted data to a Cisco Identity Services Engine or Cisco ISE Passive Identity Connector. This occurs due to an issue with how the software handles special characters, potentially allowing an attacker to gain unauthorized access, modify data, or disrupt services.

Network access and unauthenticated access required.
Specially crafted data triggers improper neutralization.
High impact to confidentiality, integrity, and availability.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an unauthenticated attacker to access sensitive information or impact the integrity and availability of Cisco Identity Services Engine and Cisco ISE Passive Identity Connector. This occurs when the product improperly handles special elements, potentially leading to unauthorized data exposure or service disruption.

Sensitive system or user data.
Improper input handling allows unauthorized access.
Compromised service integrity and availability.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Cisco Identity Services Engine (ISE) and Cisco ISE Passive Identity Connector (ISE-PIC) are critical infrastructure components likely managed by platform or network engineering teams, with oversight from security operations. The initial practical step is to confirm all instances of these products within your environment, determine their business criticality and external reachability, and identify the accountable system owner for each. Subsequent planning for remediation should be risk-based, considering maintenance windows and potential vendor coordination if applicable.

Ownership: Platform and network engineering teams.
Verify first: Identify all ISE/ISE-PIC instances.
Action: Plan remediation based on risk.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is Cisco Identity Services Engine (ISE)?

Cisco ISE is an enterprise tool used for network administration, identity management, and policy enforcement. It acts as a centralized gateway that controls who and what devices can connect to a network. Cisco ISE Passive Identity Connector is a related component that helps gather user identity information from various sources without requiring active intervention from users.

What does CWE-74 mean for CVE-2026-20130?

CVE-2026-20130 involves improper neutralization of special elements, classified under CWE-74. In plain terms, the software fails to correctly filter or handle specific characters in incoming data. Because it treats these characters as code rather than simple text, the system may unintentionally execute unauthorized commands or access data it should have protected.

How does an attacker trigger this vulnerability?

An attacker triggers this flaw by sending specially crafted data packets to the Cisco ISE or ISE-PIC software. The vulnerability requires no authentication, meaning a remote attacker does not need a valid user account to attempt the exploit. It is triggered by the system's incorrect processing of input, not by legitimate user actions like logging in normally.

Why should I care about this CVE?

You should care because Halo Surface Signal identifies these products as critical infrastructure often positioned as edge services. Because they manage network access, these systems are frequently reachable across enterprise environments. A successful attack can lead to a total loss of confidentiality, integrity, and availability of the identity services managing your network.

What are the first steps for managing this issue?

Start by identifying every instance of Cisco ISE or ISE-PIC running in your environment. Once mapped, assess which instances are accessible from the network and determine their business criticality. Coordinate with the platform or network engineering teams responsible for these systems to prioritize them for remediation based on their specific risk to your operations.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-s…

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.