CVE-2025-20376 is a vulnerability identified in the web user interface of Cisco Unified Contact Center Express (UCCX), a widely deployed contact center solution. The root cause is insufficient input validation in the file upload mechanism, which allows an authenticated attacker with administrative credentials to upload files of dangerous types that the system does not properly restrict. By uploading a malicious file, the attacker can execute arbitrary commands on the underlying operating system, potentially escalating privileges to root. This vulnerability affects a broad range of UCCX versions from 10.5(1)SU1 through 15.0.1, including many subversions and special releases. The attack vector is network-based (AV:N), requires low attack complexity (AC:L), but demands high privileges (PR:H) and no user interaction (UI:N). The vulnerability impacts confidentiality and integrity severely, as arbitrary code execution can lead to data exfiltration, system manipulation, or disruption of contact center operations. No patches or exploit code are currently publicly available, but the risk remains significant due to the critical role of UCCX in enterprise communications. The vulnerability’s CVSS score is 6.5, reflecting medium severity, but the potential for root-level compromise elevates the risk profile. Organizations relying on Cisco UCCX should prioritize mitigation to prevent exploitation.

For European organizations, the impact of this vulnerability is substantial. Cisco UCCX is commonly used in enterprise contact centers, which handle sensitive customer data and are critical for business operations. Exploitation could lead to unauthorized access to confidential customer information, disruption of contact center services, and potential lateral movement within corporate networks. The ability to execute arbitrary commands with root privileges means attackers could install persistent backdoors, manipulate call routing, or exfiltrate data undetected. This could result in regulatory non-compliance, especially under GDPR, leading to legal and financial penalties. Additionally, compromised contact centers could damage customer trust and brand reputation. The medium CVSS score underestimates the operational impact, as contact centers are often integral to customer service and business continuity. The requirement for administrative credentials limits the attack surface but does not eliminate risk, especially if credential theft or insider threats occur. The lack of known exploits in the wild provides a window for proactive defense.

1. Immediately restrict administrative access to the Cisco UCCX web UI by implementing network segmentation and limiting access to trusted IP addresses only. 2. Enforce strong multi-factor authentication (MFA) for all administrative accounts to reduce the risk of credential compromise. 3. Monitor and audit administrative login activities and file upload events for suspicious behavior. 4. Apply Cisco’s security advisories and patches as soon as they become available for affected UCCX versions. 5. If patches are not yet available, consider disabling or restricting file upload functionality in the web UI where feasible. 6. Employ Web Application Firewalls (WAF) with custom rules to detect and block malicious file upload attempts. 7. Conduct regular vulnerability assessments and penetration testing focused on administrative interfaces. 8. Educate administrators on the risks of credential sharing and phishing attacks to prevent unauthorized access. 9. Maintain up-to-date backups of UCCX configurations and data to enable rapid recovery in case of compromise. 10. Collaborate with Cisco support for guidance and incident response in case of suspected exploitation.