dbcve.org
Command InjectionWeakness · CWE-77

CVE-2025-56406

HIGH · 7.5 CVSS v3.1 Published 2025-09-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue was discovered in mcp-neo4j 0.3.0 allowing attackers to obtain sensitive information or execute arbitrary commands via the SSE service. NOTE: the Supplier's position is that authentication is not mandatory for MCP servers, and the mcp-neo4j MCP server is only intended for use in a local environment where authentication realistically would not be needed. Also, the Supplier provides middleware to help isolate the MCP server from external access (if needed).

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

The mcp-neo4j MCP server version 0.3.0 has a vulnerability in its SSE (Server-Sent Events) service that allows unauthenticated attackers to potentially obtain sensitive information from the Neo4j database and execute arbitrary commands on the host system. The SSE endpoint lacks proper authentication and authorization controls.

MitigationDeploy network isolation (firewall rules, VPC/subnet segmentation) to restrict access to trusted local users only, and utilize the supplier-provided middleware to isolate the MCP server from external network access. If remote access is required, implement additional authentication layers.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if mcp-neo4j MCP server is installed
    Check for the presence of the mcp-neo4j package in your environment using your package manager (e.g., npm list, pip list, or similar) or by searching for mcp-neo4j related files in your application directory
    Affected if The package is installed and no additional authentication is configured for the SSE endpoint
  2. Determine the installed version
    Run a command to retrieve the version of the mcp-neo4j package (e.g., npm list mcp-neo4j, pip show mcp-neo4j, or check your package-lock/package.json dependencies)
    Affected if The installed version is 0.3.0
  3. Verify if the SSE service is enabled
    Inspect your mcp-neo4j configuration files or startup scripts for SSE-related settings (commonly found in config files, environment variables, or command-line flags related to SSE or event streams)
    Affected if SSE is enabled and accessible without authentication requirements configured
  4. Check network exposure of the SSE endpoint
    Review your firewall rules, network configuration, or service binding settings to determine if the SSE port/endpoint is exposed to untrusted networks or accessible without authentication
    Affected if The SSE endpoint is bound to a network interface accessible from non-localhost sources or lacks authentication enforcement
  5. Inspect authentication configuration
    Examine configuration files, environment variables, or documentation for authentication settings specific to the SSE endpoint in the mcp-neo4j setup
    Affected if No authentication or authorization controls are explicitly configured for the SSE service

You are affected if mcp-neo4j version 0.3.0 is installed with the SSE service enabled and the endpoint is accessible without authentication controls in place.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Deploy network isolation (firewall rules, VPC/subnet segmentation) to restrict access to trusted local users only, and utilize the supplier-provided middleware to isolate the MCP server from external network access. If remote access is required, implement additional authentication layers.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-56406 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data