CVE-2025-41251 is a vulnerability classified under CWE-640, indicating a weak password recovery mechanism in VMware NSX products. The weakness lies in the password recovery process, which allows an unauthenticated remote attacker to enumerate valid usernames by interacting with the recovery functionality. This username enumeration can be leveraged to conduct targeted brute-force attacks against user credentials, increasing the likelihood of unauthorized access. The vulnerability affects multiple VMware NSX versions (9.x.x.x, 4.2.x, 4.1.x, 4.0.x), NSX-T 3.x, and VMware Cloud Foundation versions 5.x and 4.5.x that include NSX components. The CVSS v3.1 score is 8.1 (High), reflecting the vulnerability's significant impact on confidentiality, integrity, and availability, combined with the fact that exploitation requires no privileges or user interaction but has high attack complexity. No workarounds exist, but VMware has released patches in NSX 9.0.1.0, 4.2.2.2/4.2.3.1, 4.1.2.7, NSX-T 3.2.4.3, and a CCF async patch (KB88287). The vulnerability was reported by the National Security Agency, underscoring its seriousness. Although no known exploits are currently in the wild, the potential for credential brute forcing makes this a critical issue for organizations relying on NSX for network virtualization and security.

For European organizations, the vulnerability presents a substantial risk due to the widespread use of VMware NSX in data centers, cloud infrastructures, and enterprise networks. Successful exploitation could lead to unauthorized access through credential compromise, potentially allowing attackers to move laterally within networks, disrupt services, or exfiltrate sensitive data. The confidentiality of user credentials and internal network configurations is at risk, as is the integrity and availability of network virtualization services managed by NSX. Organizations in sectors such as finance, telecommunications, government, and critical infrastructure that rely heavily on NSX for network segmentation and security are particularly vulnerable. The remote and unauthenticated nature of the attack vector increases the threat surface, making it easier for attackers to target European entities without prior access. The absence of workarounds means that until patches are applied, organizations remain exposed to potential brute-force attacks facilitated by username enumeration.

European organizations should prioritize immediate deployment of the patches released by VMware for the affected NSX versions. Network administrators must verify the NSX version in use and upgrade to the fixed versions: NSX 9.0.1.0, 4.2.2.2/4.2.3.1, 4.1.2.7, NSX-T 3.2.4.3, or apply the CCF async patch (KB88287) as applicable. In parallel, organizations should enhance monitoring and alerting on authentication attempts, particularly focusing on repeated failed login attempts and unusual password recovery requests to detect brute-force activities early. Implementing rate limiting or CAPTCHA mechanisms on password recovery endpoints, if configurable, can reduce the risk of automated enumeration attacks. Additionally, enforcing strong password policies and multi-factor authentication (MFA) for NSX management interfaces can mitigate the impact of credential compromise. Network segmentation and strict access controls should be reviewed to limit the lateral movement potential of attackers who gain access. Regular security audits and penetration testing focusing on authentication mechanisms are recommended to identify residual weaknesses.