CVE-2014-2120 in ASA
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the WebVPN login page in Cisco Adaptive Security Appliance (ASA) Software allows remote attackers to inject arbitrary web script or HTML via an unspecified parameter, aka Bug ID CSCun19025.
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Analysis
by VulDB Data Team • 04/22/2026
The CVE-2014-2120 vulnerability represents a critical cross-site scripting flaw discovered in Cisco Adaptive Security Appliance (ASA) Software versions prior to 9.1(1). This vulnerability specifically affects the WebVPN login page component of the ASA platform, which serves as a primary interface for remote access authentication. The flaw resides in how the system processes user input parameters during the authentication workflow, creating an exploitable entry point for malicious actors seeking to compromise the security posture of networks protected by affected ASA devices. The vulnerability was identified through Cisco's internal security research and documented under Bug ID CSCun19025, highlighting the company's recognition of the severity associated with web-based authentication interfaces.
The technical implementation of this XSS vulnerability occurs when the WebVPN login page fails to properly sanitize or validate input parameters received from users attempting to authenticate. Attackers can exploit this weakness by crafting malicious payloads containing JavaScript code or HTML content that gets executed within the context of a victim's browser session. The unspecified parameter mentioned in the vulnerability description suggests that multiple input fields or parameters within the authentication flow may be susceptible to manipulation, potentially including username, password, or session-related fields. This weakness allows for the injection of malicious scripts that can execute in the victim's browser with the privileges of the authenticated user, effectively bypassing the security boundaries that should protect the network infrastructure.
The operational impact of CVE-2014-2120 extends beyond simple script injection, as it creates a vector for more sophisticated attacks that can compromise the entire network security infrastructure. An attacker who successfully exploits this vulnerability can potentially steal authentication tokens, session cookies, or sensitive user credentials that are processed through the WebVPN interface. The vulnerability aligns with CWE-79, which categorizes cross-site scripting as a fundamental web application security weakness, and can be mapped to ATT&CK technique T1071.004 for application layer protocol usage and T1566 for credential harvesting. Organizations using affected ASA software may experience unauthorized access to their network resources, leading to potential data breaches, privilege escalation, and complete compromise of the network perimeter protection mechanisms.
Mitigation strategies for this vulnerability require immediate implementation of Cisco's recommended security patches and updates to ASA software versions 9.1(1) and later, which contain the necessary fixes for the XSS vulnerability. Network administrators should also implement additional protective measures including input validation on all web interfaces, proper output encoding of user-supplied data, and regular security assessments of web-based management interfaces. The vulnerability demonstrates the critical importance of securing authentication interfaces, as they represent prime targets for attackers seeking to establish persistent access to network infrastructure. Organizations should also consider implementing web application firewalls to provide additional protection layers and ensure that all network devices undergo regular security audits to identify similar vulnerabilities in other components of the security infrastructure.