oss-security - CVE-2026-35554: Apache Kafka Clients: Kafka Producer Message Corruption and Misrouting via Buffer Pool Race Condition

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Message-ID: <CAMVt_AyXVuh4RV5jQ0vs3vNKR5zDxWLvDjQRnmqhX+CcVkjTdA@mail.gmail.com>
Date: Tue, 7 Apr 2026 17:18:36 +0530
From: Manikumar <manikumar@...che.org>
To: oss-security@...ts.openwall.com
Subject: CVE-2026-35554: Apache Kafka Clients: Kafka Producer Message
 Corruption and Misrouting via Buffer Pool Race Condition

Severity: moderate

Affected versions:

- Apache Kafka Clients (org.apache.kafka:kafka-clients) 2.8.0 through 3.9.1
- Apache Kafka Clients (org.apache.kafka:kafka-clients) 4.0.0 through 4.0.1
- Apache Kafka Clients (org.apache.kafka:kafka-clients) 4.1.0 through 4.1.1

Description:

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.

Credit:

Bharath Vissapragada <bharathv@...che.org> (reporter)
Donny Nadolny <donny.nadolny@...mail.com> (finder)
Donny Nadolny <donny.nadolny@...mail.com> (remediation developer)

References:
https://issues.apache.org/jira/browse/KAFKA-19012https://kafka.apache.org/community/cve-listhttps://www.cve.org/CVERecord?id=CVE-2026-35554

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