Overview

The following report delves into a critical security vulnerability identified as CVE-2025-41252. This vulnerability resides in several versions of VMware NSX and VMware Cloud Foundation (with NSX), enabling unauthenticated malicious actors to enumerate valid usernames remotely, which can potentially lead to unauthorized access attempts. Given its severity and wide impact, understanding and addressing this vulnerability is crucial for organizations relying on affected VMware products.

Vulnerability Summary

CVE ID: CVE-2025-41252
Severity: Important, CVSSv3: 7.5 (High)
Attack Vector: Remote, Unauthenticated
Privileges Required: None
User Interaction: None
Impact: Username enumeration leading to potential system compromise or data leakage

Affected Products

Product | Affected Versions

VMware NSX | 9.x.x.x, 4.2.x, 4.1.x, 4.0.x
NSX-T | 3.x
VMware Cloud Foundation (with NSX) | 5.x, 4.5.x

How the Exploit Works

The vulnerability resides in the user authentication component of the VMware NSX. An unauthenticated malicious actor can send specially crafted requests to the login interface of the affected products. These requests can disclose whether a user exists, allowing the attacker to create a list of valid usernames. With this information, the attacker can potentially carry out further attacks, such as brute-force or password spraying attacks, to gain unauthorized access.

Conceptual Example Code

Here is a conceptual example of how the vulnerability might be exploited using an HTTP request:

GET /login HTTP/1.1
Host: target.example.com
User-Agent: Mozilla/5.0
{ "username": "admin" }

In this case, the server’s response might differ depending on whether the “admin” username exists, allowing an attacker to enumerate valid usernames.

Workarounds and Mitigation

Unfortunately, no workarounds are currently available for CVE-2025-41252. The only way to effectively mitigate the vulnerability is by applying the patches provided by VMware for the affected products. Temporary measures can include the use of Web Application Firewalls (WAF) or Intrusion Detection Systems (IDS). However, these are not full-proof solutions and the recommended approach is to apply the patches as soon as possible.

Acknowledgments

This vulnerability was reported by the National Security Agency.