CVE-2025-20355 is an open redirect vulnerability found in the web-based management interface of Cisco Digital Network Architecture Center (DNA Center), a widely used network management platform. The flaw arises from improper input validation of HTTP request parameters, allowing an unauthenticated remote attacker to intercept and modify HTTP requests to redirect users to arbitrary, potentially malicious websites. This vulnerability affects a broad range of Cisco DNA Center versions, from early releases like 1.0.0.0 up to 2.3.7.9 and various AIRGAP and VA variants, indicating a long-standing and pervasive issue. The attack vector requires no privileges but does require user interaction, such as clicking a maliciously crafted URL. While the vulnerability does not directly compromise system confidentiality or availability, it can be leveraged to facilitate phishing attacks, credential harvesting, or delivery of malware by redirecting users to attacker-controlled sites. The CVSS 3.1 base score is 4.7, reflecting medium severity due to the ease of exploitation and potential for indirect impact on network integrity. No public exploits have been reported yet, but the widespread use of Cisco DNA Center in enterprise and service provider networks makes this a notable risk. The vulnerability underscores the importance of robust input validation in web interfaces managing critical network infrastructure.

For European organizations, the impact of CVE-2025-20355 primarily involves the risk of social engineering and phishing attacks facilitated by malicious redirection. Since Cisco DNA Center is used extensively for network automation and management, successful exploitation could undermine user trust and potentially lead to credential compromise if users are redirected to phishing sites mimicking legitimate Cisco portals. This could indirectly affect network integrity and operational security. Although the vulnerability does not grant direct access or control over network devices, the redirection could be a stepping stone in multi-stage attacks targeting critical infrastructure, especially in sectors like telecommunications, finance, and government. The medium severity rating reflects that while the vulnerability is not immediately critical, it poses a meaningful risk in environments where Cisco DNA Center is integral to network operations. European organizations with large Cisco deployments should consider this vulnerability a priority for mitigation to prevent exploitation that could disrupt network management workflows or lead to broader security incidents.

1. Apply official Cisco patches or updates as soon as they become available for affected DNA Center versions to address the input validation flaw directly. 2. Implement strict input validation and sanitization on all HTTP request parameters within the DNA Center interface to prevent open redirect conditions. 3. Employ web application firewalls (WAFs) with rules designed to detect and block suspicious URL redirection attempts targeting Cisco DNA Center. 4. Conduct user awareness training focused on recognizing phishing attempts and the risks of clicking unsolicited or suspicious links, especially those purporting to be from network management systems. 5. Restrict access to Cisco DNA Center management interfaces to trusted networks and users, leveraging VPNs and multi-factor authentication to reduce exposure. 6. Monitor network traffic and logs for unusual redirection patterns or access attempts that could indicate exploitation attempts. 7. Use browser security features and endpoint protection solutions that can detect and block navigation to known malicious domains. 8. Regularly review and audit Cisco DNA Center configurations and access controls to minimize attack surface and ensure compliance with security best practices.