CVE-2025-56406
CVE-2025-56406 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-77.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- EPSS exploit prediction: 0% (36th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-27549
- Weakness: CWE-77
- Published:
- Last modified:
Description
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).
Frequently asked questions
- What is CVE-2025-56406?
- 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).
- How severe is CVE-2025-56406?
- CVE-2025-56406 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
- Is CVE-2025-56406 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2025-56406?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2025-56406 have an EU (EUVD) identifier?
- Yes. CVE-2025-56406 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-27549.
- When was CVE-2025-56406 published?
- CVE-2025-56406 was published on 2025-09-10 and last updated on 2026-06-17.
References
- https://github.com/August829/CVEP/issues/1
- https://github.com/neo4j-contrib/mcp-neo4j/issues/124
- https://modelcontextprotocol.io/specification/2025-03-26/basic/authorization
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