CVE-2026-41731
HIGHCVE-2026-41731 is a high-severity (CVSS 8.1) Deserialization of Untrusted Data vulnerability in org.springframework.kafka:spring-kafka. O3 Security confirms whether CVE-2026-41731 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
In Spring for Apache Kafka, overly broad trusted-package matching in header mappers exposes JDK classes to deserialization
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-41731.
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-2026-41731 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 358,265 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-kafka☕org.springframework.kafka:spring-kafka☕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
JsonKafkaHeaderMapper and the deprecated DefaultKafkaHeaderMapper matched type headers against trusted packages using a prefix check, meaning that trusting any package implicitly trusted all of its subpackages. Combined with Jackson's default bean deserialization, a producer could supply crafted header values that caused the consumer to deserialize arbitrary JDK types.
Affected versions: Spring for Apache Kafka 4.0.0 through 4.0.5; 3.3.0 through 3.3.15; 3.2.0 through 3.2.13; 2.9.0 through 2.9.13; 2.8.0 through 2.8.11.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.springframework.kafka:spring-kafka | ≥ 4.0.0&&< 4.0.6 | 4.0.6 |
| ☕Maven | org.springframework.kafka:spring-kafka | ≥ 3.3.0&&< 3.3.16 | 3.3.16 |
| ☕Maven | org.springframework.kafka:spring-kafka | ≥ 3.2.0 | No fix |
| ☕Maven | org.springframework.kafka:spring-kafka | ≥ 2.9.0 | No fix |
| ☕Maven | org.springframework.kafka:spring-kafka | all versions | No fix |
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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.springframework.kafka:spring-kafka to 4.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41731 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 pinpoints whether CVE-2026-41731 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-41731. 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-2026-41731 in your dependencies?
O3 detects CVE-2026-41731 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.