CVE-2024-20525: Cisco Identity Services Engine XSS Vulnerability

CVE-2024-20525 Overview

CVE-2024-20525 is a reflected cross-site scripting (XSS) vulnerability in the web-based management interface of Cisco Identity Services Engine (ISE). The flaw stems from improper validation of user-supplied input in the management interface. An unauthenticated, remote attacker can exploit this issue by persuading an authenticated interface user to click a crafted link. Successful exploitation allows the attacker to execute arbitrary script code in the context of the affected interface or to access sensitive browser-based information. The vulnerability is tracked under [CWE-79] and affects multiple Cisco ISE releases from 3.0 through 3.4.

Critical Impact
Attackers can execute arbitrary JavaScript in the browser session of an ISE administrator, enabling theft of session data, credentials, or sensitive configuration information exposed through the management UI.

Affected Products

Cisco Identity Services Engine 3.0 (base and patches 1–8)
Cisco Identity Services Engine 3.1 (base and patches 1–9)
Cisco Identity Services Engine 3.2 (base and patches 1–6), 3.3 (base and patches 1–3), and 3.4

Discovery Timeline

2024-11-06 - CVE-2024-20525 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-20525

Vulnerability Analysis

Cisco ISE is a policy management platform used for network access control, device profiling, and identity-based segmentation across enterprise environments. The web-based management interface exposes administrative functions over HTTPS to authorized operators.

The vulnerability is a reflected XSS issue [CWE-79] rooted in insufficient sanitization of user-supplied input before it is echoed into responses rendered by the management interface. Because the response reflects attacker-controlled content without proper encoding, injected script executes inside the browser context of any interface user who follows a crafted link.

Exploitation requires user interaction and does not require prior authentication to the ISE interface. The scope is changed, meaning the injected script can affect resources beyond the vulnerable component, such as other browser origins, tabs, or session artifacts accessible to the targeted administrator.

Root Cause

The root cause is missing or inadequate input validation and output encoding on parameters processed by the ISE web management interface. User-controlled values are placed into HTML or JavaScript contexts without escaping, allowing an attacker-supplied payload to break out of data context and execute as script.

Attack Vector

The attack is network-based and requires social engineering. An attacker crafts a URL to the target ISE interface containing a malicious script payload in a vulnerable parameter. The attacker then delivers this link to an ISE user through email, chat, or a compromised web page. When the user clicks the link while authenticated to the interface, the payload executes with the privileges and browser context of that session, permitting session token theft, forced administrative actions, or exfiltration of data visible to the user.

No verified public exploit code is available for this vulnerability. Refer to the Cisco Security Advisory on ISE Vulnerabilities for vendor technical details.

Detection Methods for CVE-2024-20525

Indicators of Compromise

HTTP requests to ISE management interface endpoints containing script tags, javascript: URIs, or common XSS payload markers such as onerror=, onload=, or encoded variants
Referrer headers pointing to external domains or webmail services when ISE administrative sessions are accessed
Unexpected outbound requests from administrator browsers to attacker-controlled hosts shortly after ISE UI activity

Detection Strategies

Inspect web server and reverse proxy logs for ISE URLs containing suspicious query string content, HTML metacharacters (<, >, ", '), or URL-encoded script fragments
Deploy a web application firewall in front of ISE with signatures for reflected XSS payload patterns targeting query parameters and form fields
Correlate administrator login events with browser telemetry to identify anomalous script execution or DOM modification during ISE sessions

Monitoring Recommendations

Enable and forward ISE application and access logs to a centralized SIEM for query-string and payload inspection
Monitor phishing and email gateway telemetry for links pointing to internal ISE hostnames or management URLs
Alert on administrator sessions originating from unusual geolocations, user agents, or immediately following email link clicks

How to Mitigate CVE-2024-20525

Immediate Actions Required

Upgrade Cisco ISE to a fixed release as identified in the vendor advisory for versions 3.0 through 3.4
Restrict access to the ISE web-based management interface to a dedicated administrative network segment or jump hosts
Educate administrators to avoid clicking links to ISE URLs received from untrusted sources and to log out of the interface when not in use

Patch Information

Cisco has published fixed software for affected Identity Services Engine releases. Apply the updates listed in the Cisco Security Advisory on ISE Vulnerabilities, which addresses this XSS issue alongside additional ISE flaws disclosed in the same bulletin. Cisco does not indicate a workaround, so patching is the primary remediation path.

Workarounds

Limit management interface reachability using ACLs, firewall policies, or VPN-only administrative access to reduce the attack surface for crafted-link delivery
Enforce short administrative session timeouts and require re-authentication for sensitive actions to reduce the value of a hijacked session
Use browser isolation or dedicated administrative browsers for ISE management to contain the impact of injected script

bash

# Example ACL restricting ISE admin UI (TCP/443) to a management subnet
ip access-list extended ISE-ADMIN-ACCESS
  permit tcp 10.10.50.0 0.0.0.255 host <ISE_PAN_IP> eq 443
  deny   tcp any host <ISE_PAN_IP> eq 443 log
  permit ip any any