# CVE-2026-35554: Apache Kafka Kafka Clients race condition in Kafka Producer

Source: https://junglewise.ai/threats/cve-2026-35554-apache-kafka-kafka-clients-race-condition-in-kafka-producer  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-07. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2026-35554 · Severity: high · CVSS 8.7 · Published 2026-04-07

A race condition in the Apache Kafka Java client can cause messages to be silently sent to the wrong destination. This occurs when internal memory buffers are reused too quickly, potentially exposing sensitive data to unauthorized users or causing data corruption in downstream systems. Organizations using Kafka for data streaming should update their client libraries to prevent silent data misrouting.

Technologies: [Apache Kafka](https://junglewise.ai/threats/technologies/kafka), [org.apache.kafka:kafka-clients (Maven)](https://junglewise.ai/threats/technologies/org-apache-kafka-kafka-clients). Vendors: [Apache](https://junglewise.ai/threats/vendors/apache), [Apache Software Foundation](https://junglewise.ai/threats/vendors/apache-software-foundation), [Maven](https://junglewise.ai/threats/vendors/maven).

## Quick answers

**Is CVE-2026-35554 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-35554 being exploited in the wild.

**How severe is CVE-2026-35554?** High severity, with a CVSS score of 8.7, published 7 April 2026.

**Which products and versions are affected?** Apache Software Foundation Kafka Clients >= 2.8.0, < 3.9.2; >= 4.0.0, < 4.0.2; >= 4.1.0, < 4.1.2; org.apache.kafka:kafka-clients (Maven) ECOSYSTEM:introduced=2.8.0,fixed=3.9.2.

**Is there a fix for CVE-2026-35554?** Yes. org.apache.kafka:kafka-clients (Maven): upgrade to 3.9.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-35554 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-35554?** Check whether you run Apache Kafka, Apache Software Foundation Kafka Clients or org.apache.kafka:kafka-clients (Maven) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- org.apache.kafka:kafka-clients (Maven): upgrade to 3.9.2 or later

  ```sh
  # set org.apache.kafka:kafka-clients to 3.9.2 in your pom.xml or build.gradle
  ```


## Technical details

A race condition exists in the Apache Kafka Java producer client's buffer pool management (CWE-362). When a produce batch expires due to 'delivery.timeout.ms' while a network request is still in flight, the batch's ByteBuffer is prematurely deallocated and returned to the pool. If a subsequent batch reuses this buffer before the original request completes, the buffer contents may be corrupted or misrouted to an unintended topic. This occurs without reporting an error to the producer, leading to potential confidentiality breaches and data integrity issues. The vulnerability is reachable over the network but requires specific timing conditions (high complexity). Fixes are available in versions 3.9.2, 4.0.2, 4.1.2, and 4.2.0.

## Affected products

- Apache kafka-clients >= 2.8.0, < 3.9.2; >= 4.0.0, < 4.0.2; >= 4.1.0, < 4.1.2

## Identifiers

- CVE-2026-35554
- GHSA-5qcv-4rpc-jp93

## Timeline

- 2026-04-07: disclosed
- 2026-04-07: advisory

## References

- [https://api.github.com/users/filipecamargos](https://api.github.com/users/filipecamargos)
- [https://github.com/filipecamargos](https://github.com/filipecamargos)
- [https://api.github.com/users/filipecamargos/gists%7B/gist_id%7D](https://api.github.com/users/filipecamargos/gists%7B/gist_id%7D)
- [https://api.github.com/users/filipecamargos/repos](https://api.github.com/users/filipecamargos/repos)
- [https://avatars.githubusercontent.com/u/55758354?v=4](https://avatars.githubusercontent.com/u/55758354?v=4)
- [https://api.github.com/users/filipecamargos/events%7B/privacy%7D](https://api.github.com/users/filipecamargos/events%7B/privacy%7D)

## Related threats

- [Apache Kafka incorrect operator in FetchSnapshot RPC handler](https://junglewise.ai/threats/cve-2026-83525-incorrect-operator-cwe-480-in-the-fetchsnapshot-rpc-handler-in)
- [Apache Kafka memory exhaustion in compressed record batch decoding](https://junglewise.ai/threats/cve-2026-114349-when-a-broker-decodes-a-compressed-record-batch-the-per-record)
- [Apache Kafka information disclosure via ConfigProvider in AlterConfigs](https://junglewise.ai/threats/cve-2026-112375-an-authenticated-kafka-principal-with-no-authorization-grants)
- [Apache Kafka deserialization denial of service via oversized allocation](https://junglewise.ai/threats/cve-2026-111551-several-kafka-deserialization-paths-read-a-size-or-count-field)
- [Apache Kafka unbounded tagged-field allocation in flexible protocol headers](https://junglewise.ai/threats/cve-2026-111115-apache-kafka-s-code-generated-readers-for-flexible-protocol)