CVE-2025-20342 in Unified Computing System
Summary
by MITRE • 08/27/2025
A vulnerability in the Virtual Keyboard Video Monitor (vKVM) connection handling of Cisco Integrated Management Controller (IMC) could allow an authenticated, remote attacker with low privileges to conduct a stored cross-site scripting (XSS) attack against a user of the interface.
This vulnerability is due to insufficient validation of user-supplied input by the web-based management interface of an affected system. An attacker could exploit this vulnerability by injecting malicious code into a specific data field in the interface. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information. To exploit this vulnerability, the attacker must have valid user credentials with privileges that allow for vKVM access on the affected device. Note: The affected vKVM client is also included in Cisco UCS Manager.
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Analysis
by VulDB Data Team • 09/08/2025
The vulnerability identified as CVE-2025-20342 resides within the Virtual Keyboard Video Monitor functionality of Cisco Integrated Management Controller systems, representing a critical security weakness that enables authenticated remote attackers to execute stored cross-site scripting attacks. This flaw specifically impacts the web-based management interface of affected Cisco devices, creating a pathway for malicious actors to inject persistent malicious code into data fields that are subsequently rendered to unsuspecting users. The vulnerability stems from inadequate input validation mechanisms within the vKVM connection handling process, allowing attackers to store malicious payloads that execute when other users interact with the compromised interface. The attack vector requires an authenticated session with sufficient privileges to access the vKVM functionality, making it particularly concerning as it targets users who already possess legitimate access to management interfaces. This vulnerability is classified under CWE-79, which specifically addresses Cross-Site Scripting flaws in web applications, and aligns with ATT&CK technique T1059.007 for Scripting, as it enables execution of malicious scripts within the victim's browser context. The affected systems include Cisco Integrated Management Controller devices where vKVM functionality is enabled, with the vulnerability also extending to Cisco UCS Manager systems that incorporate the same vKVM client component.
The technical exploitation of this vulnerability involves an attacker leveraging their legitimate vKVM access privileges to inject malicious JavaScript code into input fields within the web interface. Once the malicious payload is stored in the system's data handling mechanisms, it becomes persistent and executes whenever the affected interface is accessed by other users. The stored XSS attack allows for arbitrary code execution in the context of the victim's browser session, potentially enabling attackers to steal session cookies, redirect users to malicious sites, or extract sensitive information from the browser's memory. The vulnerability's impact extends beyond simple script execution as it can facilitate more sophisticated attacks such as credential theft, session hijacking, or data exfiltration. The attacker's ability to leverage existing valid credentials for exploitation makes this attack particularly dangerous as it bypasses many traditional authentication-based security controls. The web interface's insufficient sanitization of user-supplied input creates a persistent threat vector that remains active until the vulnerability is patched or the malicious data is manually removed from the system.
The operational impact of CVE-2025-20342 extends beyond immediate script execution to encompass broader security implications for organizations relying on Cisco IMC and UCS Manager systems. Attackers could potentially escalate their privileges through session manipulation, gain unauthorized access to sensitive management functions, or use the compromised interface as a pivot point for attacking other systems within the network. The vulnerability's persistence means that even after initial exploitation, the malicious code continues to affect users until the system is properly patched or the stored data is cleared. Organizations may experience unauthorized access to critical infrastructure management functions, leading to potential service disruptions, data compromise, or unauthorized configuration changes. The impact is particularly severe in enterprise environments where IMC systems manage multiple devices and where the vKVM functionality is frequently used for remote troubleshooting and system administration. The vulnerability also affects the integrity of the management interface, potentially compromising the trust model that users place in the system's security controls.
Mitigation strategies for CVE-2025-20342 should prioritize immediate patch deployment from Cisco, as this represents the most effective defense against the vulnerability. Organizations should also implement network segmentation to limit access to vKVM functionality to only authorized personnel and critical systems. Input validation should be enhanced at multiple layers including web application firewalls and application-level controls to prevent malicious code injection. Regular security audits of web interfaces should be conducted to identify similar validation weaknesses that could be exploited in similar fashion. Access controls should be strictly enforced using principle of least privilege, ensuring that only necessary personnel have vKVM access privileges. Security monitoring should be enhanced to detect unusual patterns in vKVM usage and data field modifications. Organizations should also consider implementing user awareness training to help identify potential XSS attack indicators and establish incident response procedures specifically for managing web-based attack vectors. The vulnerability's classification under both CWE-79 and ATT&CK T1059.007 emphasizes the need for comprehensive defensive measures that address both the technical implementation flaw and the broader attack methodology that attackers employ to exploit such weaknesses.