Summary
Neo4j Labs MCP Servers: SSRF and Data Modification via read_only Mode Bypass Through CALL Procedures
The read_only mode in mcp-neo4j-cypher versions prior to 0.6.0 can be bypassed using CALL procedures.
Details
Notes
Impacts for server-side request forgery vulnerabilities may depend on both the configuration of the vulnerable system as well as the presence of other systems in the environment that could be accessed as part of exploitation.
Recommended hardening
- Limit the apoc procedures to what's required
- Manage data loading privileges
- Don't relax the default settings without compensating controls
apoc.import.file.enabledisfalseby defaultapoc.import.file.use_neo4j_configistrueby default to restrict file imports to the import folder
Credits
We want to publicly recognise the contribution of Yotam Perkal from Pluto Security.
Impact
The enforcing of read_only mode in vulnerable versions could be bypassed by certain APOC procedures.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
v0.6.0 release hardened the checks around the mode. The only way to guarantee the server actions is to limit the permissions of the db credentials available to the server.
Frequently Asked Questions
- What is CVE-2026-35402? CVE-2026-35402 is a low-severity security vulnerability in mcp-neo4j-cypher (pip), affecting versions < 0.6.0. It is fixed in 0.6.0.
- Which versions of mcp-neo4j-cypher are affected by CVE-2026-35402? mcp-neo4j-cypher (pip) versions < 0.6.0 is affected.
- Is there a fix for CVE-2026-35402? Yes. CVE-2026-35402 is fixed in 0.6.0. Upgrade to this version or later.
- Is CVE-2026-35402 exploitable, and should I be worried? Whether CVE-2026-35402 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-35402 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-35402? Upgrade
mcp-neo4j-cypherto 0.6.0 or later.