CVE-2025-20353: Cisco Catalyst Center XSS Vulnerability

CVE-2025-20353 Overview

CVE-2025-20353 is a reflected cross-site scripting (XSS) vulnerability in the web-based management interface of Cisco Catalyst Center. The flaw stems from insufficient validation of user-supplied input processed by the interface. An unauthenticated, remote attacker can exploit the issue by persuading an authenticated user to click a crafted link. Successful exploitation executes arbitrary script code in the user's browser session or exposes sensitive browser-based information, including session data. The weakness is tracked under CWE-79: Improper Neutralization of Input During Web Page Generation.

Critical Impact
Attackers can execute arbitrary JavaScript in the context of a Catalyst Center administrator's browser, enabling session hijacking, credential theft, and unauthorized actions against network infrastructure managed by the platform.

Affected Products

Cisco Catalyst Center (formerly Cisco DNA Center)
Cisco Catalyst Center web-based management interface
Deployments exposing the management UI to user-accessible browsers

Discovery Timeline

2025-11-13 - CVE-2025-20353 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-20353

Vulnerability Analysis

The vulnerability resides in the web-based management interface of Cisco Catalyst Center, the centralized controller for Cisco Catalyst switching and SD-Access fabrics. The interface fails to properly neutralize user-controlled input before reflecting it in HTTP responses rendered by the browser. When a targeted user follows a crafted URL, the malicious payload is embedded into the response page and executed by the browser under the origin of the Catalyst Center interface.

The scope is marked as changed, meaning code executed via the vulnerable component can affect resources beyond its own security scope, such as other browser contexts or authenticated sessions. User interaction is required because delivery depends on the victim clicking a crafted link, typically distributed through phishing, chat platforms, or embedded content.

Root Cause

The root cause is insufficient input validation and output encoding in a parameter handled by the Catalyst Center web UI. Reflected input is rendered into HTML or JavaScript execution contexts without appropriate escaping, permitting injection of <script> payloads or event-handler attributes. This is a classic instance of CWE-79, Improper Neutralization of Input During Web Page Generation.

Attack Vector

Exploitation follows a standard reflected XSS pattern. The attacker crafts a URL to the Catalyst Center management interface containing a malicious payload in a vulnerable parameter. The attacker delivers the URL to an authenticated administrator through email, messaging, or a compromised web page. When the victim clicks the link while logged in, the browser executes the injected script in the interface's origin.

Post-exploitation actions include exfiltrating session cookies, submitting authenticated requests to Catalyst Center APIs, harvesting network topology data, or modifying device configurations through the administrator's session. Refer to the Cisco Security Advisory for vendor-confirmed technical details.

// No verified proof-of-concept code is publicly available.
// See the Cisco Security Advisory referenced above for vendor details.

Detection Methods for CVE-2025-20353

Indicators of Compromise

HTTP requests to Catalyst Center URLs containing script tags, javascript: URIs, or common XSS payload markers such as onerror=, onload=, or alert(
Referer headers pointing to unfamiliar third-party domains preceding Catalyst Center session activity
Unexpected outbound requests from administrator browsers to attacker-controlled hosts following interaction with a Catalyst Center link

Detection Strategies

Inspect web application firewall and reverse proxy logs for encoded payloads (%3Cscript%3E, %22%3E%3Cimg) targeting Catalyst Center query parameters
Correlate Catalyst Center authentication events with browser-based anomalies such as new API tokens or unexpected configuration changes
Deploy signatures that match reflected XSS patterns against the Catalyst Center management interface hostname

Monitoring Recommendations

Enable audit logging within Catalyst Center and forward events to a centralized analytics platform for correlation with endpoint and network telemetry
Monitor administrator endpoints for browser process anomalies, credential access, and unusual outbound connections initiated from browser sessions
Track email and messaging gateways for links pointing to internal Catalyst Center management URLs originating from external senders

How to Mitigate CVE-2025-20353

Immediate Actions Required

Apply the fixed Catalyst Center software release identified in the Cisco Security Advisory
Restrict access to the Catalyst Center web-based management interface to a dedicated management network and jump hosts
Educate administrators to avoid clicking Catalyst Center URLs received through untrusted channels

Patch Information

Cisco has published a security advisory tracked as cisco-sa-dnac-xss-weXtVZ59 documenting fixed software releases. Administrators should consult the Cisco Security Advisory for the specific fixed version applicable to their deployment and follow Cisco's standard upgrade procedures.

Workarounds

Cisco has not published a supported workaround; upgrading to a fixed release is the only vendor-endorsed remediation
Enforce network segmentation and access control lists to limit which client IPs can reach the Catalyst Center UI
Require administrators to use dedicated privileged access workstations for Catalyst Center sessions to reduce phishing exposure

bash

# Example ACL concept restricting management UI access to a jump host subnet
# Apply on upstream firewall or load balancer in front of Catalyst Center
access-list CATALYST_MGMT permit tcp 10.10.50.0/24 host <catalyst-center-ip> eq 443
access-list CATALYST_MGMT deny   tcp any host <catalyst-center-ip> eq 443