A race condition in the Apache Kafka Java producer client’s buffer pool management can cause messages to be silently delivered to incorrect topics. When a produce batch expires due to delivery.timeout.ms while a network request containi…

Overview

A race condition in the Apache Kafka Java producer client’s buffer pool management can cause messages to be silently delivered to incorrect topics.

When a produce batch expires due to delivery.timeout.ms while a network request containing that batch is still in flight, the batch’s ByteBuffer is prematurely deallocated and returned to the buffer pool. If a subsequent producer batch—potentially destined for a different topic—reuses this freed buffer before the original network request completes, the buffer contents may become corrupted. This can result in messages being delivered to unintended topics without any error being reported to the producer.

Data Confidentiality: Messages intended for one topic may be delivered to a different topic, potentially exposing sensitive data to consumers who have access to the destination topic but not the intended source topic.

Data Integrity: Consumers on the receiving topic may encounter unexpected or incompatible messages, leading to deserialization failures, processing errors, and corrupted downstream data.

This issue affects Apache Kafka versions ≤ 3.9.1, ≤ 4.0.1, and  ≤ 4.1.1.

Kafka users are advised to upgrade to 3.9.2, 4.0.2, 4.1.2, 4.2.0, or later to address this vulnerability.

Affected

• kafka >= 2.8.0, < 3.9.2
• kafka >= 4.0.0, < 4.0.2
• kafka >= 4.1.0, < 4.1.2

Remediation

Upgrade past the affected range:

• kafka 4.1.2

Vendor advisories

• RHSA-2026:42098 · Red Hat · fixed in: Red Hat JBoss Enterprise Application Platform 6.0.5.GA · released 2026-07-20 · advisory
• RHSA-2026:17668 · Red Hat · fixed in: Red Hat build of Apache Camel 4.18.1 for Spring Boot 3.5.14 · released 2026-05-14 · advisory
• RHSA-2026:11721 · Red Hat · fixed in: Red Hat build of Quarkus 3.27.3.SP1 · released 2026-05-05 · advisory
• RHSA-2026:54435 · Red Hat · fixed in: Streams for Apache Kafka 3.2.1 · released 2026-08-12 · advisory
• Red Hat VEX · Moderate · affected: OpenShift Serverless, Red Hat build of Apache Camel 4 for Quarkus 3, Red Hat build of Apicurio Registry 2, Red Hat build of Apicurio Registry 3, Red Hat build of Debezium 2, Red Hat build of Debezium 3, … · no fix planned: Red Hat build of Debezium 2, Red Hat Fuse 7, Red Hat JBoss Enterprise Application Platform 7, Red Hat Process Automation 7, … · updated 2026-10-20 · vex
• RHSA-2026:13631 · Red Hat · fixed in: Red Hat Build of Apache Camel 4.14 for Quarkus 3.27 · released 2026-05-05 · advisory