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CRITICAL severity

Deserialization of Untrusted Data in Neo4jGHSA-pc4w-8v5j-29w9

CRITICAL

GHSA-pc4w-8v5j-29w9 is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in org.neo4j:neo4j. 3 public exploit references exist, so weaponization risk is real. A fix is available for org.neo4j:neo4j — see the affected versions and patch details below.

Also known asBIT-neo4j-2021-34371BIT-neo4j-enterprise-2021-34371CVE-2021-34371
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
3 known
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
13.4%probability of exploitation in next 30 days
Moderate Risk0.00%
Lower risk than most CVEs96th percentile — riskier than 96% of all scored CVEsHighest risk
0.00%28.2%56.3%84.5%64.9%13.4%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-pc4w-8v5j-29w9 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
☕org.neo4j:neo4j

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Neo4j through 3.4.18 (with the shell server enabled) exposes an RMI service that arbitrarily deserializes Java objects, e.g., through setSessionVariable. An attacker can abuse this for remote code execution because there are dependencies with exploitable gadget chains.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.neo4j:neo4jall versions3.5.0org.neo4j:neo4j:3.5.0

Affected Products

1 product · 1 configurations
Application
neo4jneo4j
≤ 3.4.18
range
Exploits & PoCs
3

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Neo4j through 3.4.18 (with the shell server enabled) exposes an RMI serv…

exploit-db.comNVDAug 2021

Neo4j through 3.4.18 (with the shell server enabled) exposes an RMI serv…

github.comGithubSep 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.neo4j:neo4j, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.neo4j:neo4j to 3.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-pc4w-8v5j-29w9 is resolved across your whole dependency graph.

  3. Workarounds

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

Neo4j through 3.4.18 (with the shell server enabled) exposes an RMI service that arbitrarily deserializes Java objects, e.g., through setSessionVariable. An attacker can abuse this for remote code execution because there are dependencies with exploitable gadget chains.
O3 Security · Impact-Aware SCA

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Deserialization of Untrusted Data in Neo4j (Critical 9.8)