CVE-2023-34040 — spring-kafka
MEDIUMCVE-2023-34040 is a medium-severity (CVSS 5.3) Deserialization of Untrusted Data vulnerability in org.springframework.kafka:spring-kafka. 4 public exploit references exist, so weaponization risk is real. A fix is available for org.springframework.kafka:spring-kafka — see the affected versions and patch details below.
Java Deserialization vulnerability in Spring-Kafka When Improperly Configured
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-34040.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-34040 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,238 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.springframework.kafka:spring-kafka☕org.springframework.kafka:spring-kafkaReal-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
In Spring for Apache Kafka 3.0.9 and earlier and versions 2.9.10 and earlier, a possible deserialization attack vector existed, but only if unusual configuration was applied. An attacker would have to construct a malicious serialized object in one of the deserialization exception record headers.
Specifically, an application is vulnerable when all of the following are true:
- The user does not configure an ErrorHandlingDeserializer for the key and/or value of the record
- The user explicitly sets container properties checkDeserExWhenKeyNull and/or checkDeserExWhenValueNull container properties to true.
- The user allows untrusted sources to publish to a Kafka topic
By default, these properties are false, and the container only attempts to deserialize the headers if an ErrorHandlingDeserializer is configured. The ErrorHandlingDeserializer prevents the vulnerability by removing any such malicious headers before processing the record.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.springframework.kafka:spring-kafka | ≥ 2.8.1&&< 2.9.11 | 2.9.11org.springframework.kafka:spring-kafka:2.9.11 |
| ☕Maven | org.springframework.kafka:spring-kafka | ≥ 3.0.0&&< 3.0.10 | 3.0.10org.springframework.kafka:spring-kafka:3.0.10 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.springframework.kafka:spring-kafka, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.springframework.kafka:spring-kafka to 2.9.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-34040 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-34040 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-34040. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-34040 in your dependencies?
O3 Security finds CVE-2023-34040 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.