NSX: Observable Discrepancy
CVE-2025-41252 is a high-severity observable discrepancy vulnerability in NSX from VMware, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected NSX versions: VMware NSX 9.x.x.x, 4.2.x, 4.1.x, 4.0.x; VMware NSX-T 3.x; VMware Cloud Foundation (with NSX) 5.x, 4.5.x. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.71% chance of exploitation within 30 days, higher than 54% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of NSX you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| VMware | NSX | VMware NSX 9.x.x.x, 4.2.x, 4.1.x, 4.0.x; VMware NSX-T 3.x; VMware Cloud Foundation (with NSX) 5.x, 4.5.x | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by CNA (vmware.com).
Official description
Description: VMware NSX contains a username enumeration vulnerability. An unauthenticated malicious actor may exploit this to enumerate valid usernames, potentially leading to unauthorized access attempts. Impact: Username enumeration → facilitates unauthorized access. Attack Vector: Remote, unauthenticated. Severity: Important. CVSSv3: 7.5 (High). Acknowledgments: Reported by the National Security Agency. Affected Products: * 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 Fixed Versions: * NSX 9.0.1.0; 4.2.2.2/4.2.3.1 http://4.2.2.2/4.2.3.1 ; 4.1.2.7; NSX-T 3.2.4.3; CCF async patch (KB88287). Workarounds: None.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Observable Discrepancy
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
How developers prevent this class of flaw
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in NSX
- 8.1 High severity
Recent Observable Discrepancy vulnerabilities
- 9.1 Critical severity
- 7.0 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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