CVE-2025-21104 is classified as a CWE-601 'URL Redirection to Untrusted Site' vulnerability affecting Dell NetWorker Management Console in versions prior to 19.11.0.4 and version 19.12. The vulnerability allows an unauthenticated attacker with remote access to craft URLs that cause the application to redirect targeted users to arbitrary external websites. This open redirect flaw arises because the application fails to properly validate or restrict redirect URLs, enabling attackers to exploit the trust users place in the legitimate NetWorker interface. While the vulnerability does not directly compromise confidentiality, integrity, or availability of the NetWorker system itself, it can be leveraged to conduct sophisticated phishing campaigns. Attackers can send malicious links appearing to originate from a trusted Dell NetWorker console, increasing the likelihood that users will disclose credentials or other sensitive data on attacker-controlled sites. The vulnerability requires no authentication but does require user interaction to follow the malicious redirect. The CVSS v3.1 base score is 4.3, reflecting network attack vector, low complexity, no privileges required, but user interaction needed and limited confidentiality impact. No public exploits have been reported to date, but the vulnerability is publicly disclosed and should be considered a phishing enabler rather than a direct system compromise vector.

For European organizations, the primary impact of CVE-2025-21104 is an increased risk of successful phishing attacks targeting users of Dell NetWorker Management Console. This could lead to credential theft, unauthorized access to internal systems, or data leakage if users are tricked into submitting sensitive information on malicious sites. While the vulnerability does not directly affect the availability or integrity of backup operations, compromised credentials or session tokens obtained via phishing could indirectly lead to broader security incidents, including ransomware or data exfiltration. Organizations in sectors with high reliance on data backup and recovery, such as finance, healthcare, and critical infrastructure, may face elevated risks. The vulnerability's exploitation could also undermine user trust in IT management tools, complicating incident response and recovery efforts. Given the remote and unauthenticated nature of the vulnerability, attackers can target users across multiple organizations without needing prior access, increasing the threat surface.

To mitigate CVE-2025-21104, European organizations should: 1) Immediately upgrade Dell NetWorker Management Console to versions later than 19.11.0.4 or versions where the vulnerability is patched, as Dell’s official patch or update becomes available. 2) Implement strict URL validation and filtering on any web proxies or gateways that handle traffic to the NetWorker console, blocking suspicious redirect URLs. 3) Educate users on recognizing phishing attempts, especially those involving links originating from trusted internal tools. 4) Employ multi-factor authentication (MFA) on NetWorker Management Console access to reduce the impact of credential compromise. 5) Monitor logs for unusual redirect URL patterns or unexpected user navigation events. 6) Consider deploying web isolation or browser security tools that can contain malicious redirects. 7) If patching is delayed, restrict remote access to the NetWorker Management Console to trusted networks or VPNs to reduce exposure. These targeted measures go beyond generic advice by focusing on the specific attack vector and user behavior exploitation.