CVE-2024-20443: Cisco Identity Services Engine XSS Flaw

CVE-2024-20443 Overview

A Cross-Site Scripting (XSS) vulnerability exists in the web-based management interface of Cisco Identity Services Engine (ISE). This vulnerability allows an authenticated, remote attacker with at least low-privileged access to inject malicious code into specific pages of the interface, potentially executing arbitrary script code in the context of the affected interface or accessing sensitive browser-based information.

The vulnerability stems from insufficient validation of user-supplied input by the web-based management interface. Attackers who have obtained low-privileged credentials can exploit this flaw to target other users of the ISE management interface, including administrators with elevated privileges.

Critical Impact

Successful exploitation could allow attackers to execute arbitrary JavaScript in the context of authenticated administrator sessions, potentially leading to session hijacking, credential theft, or unauthorized configuration changes to network access policies.

Affected Products

• Cisco Identity Services Engine 2.7.0 (base and patches 1-10)
• Cisco Identity Services Engine 3.0.0 (base and patches 1-6, 8)
• Cisco Identity Services Engine 3.1.0 (base and patches 1-8)
• Cisco Identity Services Engine 3.2.0 (base and patches 1-6)
• Cisco Identity Services Engine 3.3.0 (base and patches 1-2)

Discovery Timeline

• August 7, 2024 - CVE-2024-20443 published to NVD
• October 2, 2025 - Last updated in NVD database

Technical Details for CVE-2024-20443

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The flaw exists within the web-based management interface of Cisco ISE, a critical network access control platform used for identity management, policy enforcement, and network segmentation.

The vulnerability requires authentication to exploit, meaning an attacker must first possess valid credentials for a low-privileged account on the affected device. Once authenticated, the attacker can inject malicious scripts into specific pages within the management interface. When another user—particularly an administrator—views these affected pages, the injected script executes within their browser session.

Given that Cisco ISE serves as a centralized policy management platform for enterprise networks, successful exploitation could have significant downstream effects on network security posture. An attacker who compromises an administrator session could potentially modify authentication policies, create backdoor accounts, or access sensitive network configuration data.

Root Cause

The root cause of this vulnerability is insufficient validation and sanitization of user-supplied input within the Cisco ISE web-based management interface. The affected pages fail to properly encode or escape user-controlled data before rendering it in the HTML response, allowing specially crafted input containing JavaScript code to be interpreted and executed by the victim's browser.

This represents a stored XSS vulnerability where the malicious payload persists within the application and is served to other users who access the affected pages.

Attack Vector

The attack vector is network-based and requires the following conditions:

1. The attacker must have network access to the Cisco ISE management interface
2. The attacker must possess valid credentials for at least a low-privileged account
3. User interaction is required—a victim must navigate to the page containing the injected payload

The attack flow typically proceeds as follows: the attacker authenticates to the ISE management interface using low-privileged credentials, navigates to a vulnerable page, and submits malicious JavaScript code through an input field. This payload is stored by the application. When another user (particularly an administrator) views the affected page, the malicious script executes in their browser context, potentially allowing session token theft, keylogging, or arbitrary actions performed on behalf of the victim.

Detection Methods for CVE-2024-20443

Indicators of Compromise

• Unusual JavaScript payloads or encoded script tags in ISE management interface input fields
• Unexpected HTTP requests originating from administrator browsers to external domains
• Authentication logs showing low-privileged accounts accessing administrative configuration pages
• Browser console errors or unexpected script execution on ISE management pages

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect common XSS patterns in requests to ISE management interface
• Monitor ISE audit logs for suspicious input patterns containing script tags, event handlers, or JavaScript URIs
• Implement Content Security Policy (CSP) headers to restrict script execution sources and detect policy violations
• Review ISE access logs for unusual patterns of page access by low-privileged accounts

Monitoring Recommendations

• Enable detailed logging on the Cisco ISE management interface to capture all user input submissions
• Configure SIEM alerts for patterns indicative of XSS payloads in web traffic to ISE management ports
• Monitor for unusual session behavior such as simultaneous access from different IP addresses
• Track changes to ISE policies and user accounts that occur outside normal change windows

How to Mitigate CVE-2024-20443

Immediate Actions Required

• Update Cisco ISE to a patched version as specified in the Cisco Security Advisory
• Restrict network access to the ISE management interface to trusted administrative networks only
• Review and audit all low-privileged accounts for legitimacy and necessity
• Implement multi-factor authentication (MFA) for ISE management interface access

Patch Information

Cisco has released security updates to address this vulnerability. Administrators should consult the Cisco Security Advisory for detailed patch information and upgrade paths specific to their ISE deployment version.

Organizations should prioritize patching based on their exposure—deployments with management interfaces accessible from less-trusted network segments should be updated with urgency.

Workarounds

• Limit management interface access to dedicated administrative workstations on isolated network segments
• Implement browser security extensions on administrator workstations to detect and block XSS attempts
• Configure firewall rules to restrict outbound connections from the ISE management interface
• Use separate browsers or browser profiles for ISE administration to limit cookie scope

# Example: Restrict ISE management interface access via ACL
# Apply to network infrastructure protecting ISE management interface
ip access-list extended ISE-MGMT-RESTRICT
 permit tcp 10.10.10.0 0.0.0.255 host 192.168.1.100 eq 443
 deny tcp any host 192.168.1.100 eq 443 log
 permit ip any any