CVE-2026-35402: mcp-neo4j-cypher: SSRF and Data Modification via read_only Mode Bypass Through CALL Procedures

Severity: low (CVSS 2.3 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-17 · updated 2026-06-17
Weakness: CWE-284

Description

mcp-neo4j-cypher is an MCP server for executing Cypher queries against Neo4j databases. In versions prior to 0.6.0, the read_only mode enforcement can be bypassed using APOC CALL procedures, potentially allowing unauthorized write operations or server-side request forgery. This issue is fixed in version 0.6.0.

Affected products

neo4j-contrib mcp-neo4j: before 0.6.0

References

https://github.com/neo4j-contrib/mcp-neo4j/releases/tag/mcp-neo4j-cypher-v0.6.0
https://github.com/neo4j-contrib/mcp-neo4j/security/advisories/GHSA-x3cv-r3g3-fpg9

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