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

What is CVE-2026-35554?

CVE-2026-35554 is a high-severity vulnerability in Apache Kafka Clients, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-416, CWE-362

Which versions are affected by CVE-2026-35554?

6 open source packages ship an affected version, including org.apache.kafka:kafka-clients. It affects 1 product.

Products include Apache Kafka.

How do I fix CVE-2026-35554?

Upgrade org.apache.kafka:kafka-clients to a fixed version for your release line: 3.9.2, 4.0.2 or 4.1.2.

Is CVE-2026-35554 being exploited?

There is no known exploitation of CVE-2026-35554 in the wild and no public exploit code.

Other vulnerabilities in Apache Kafka Clients

• CVE-2026-33557 Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication Critical 9.1
• CVE-2025-27818 Apache Kafka: Possible RCE attack via SASL JAAS LdapLoginModule configuration High 8.8
• CVE-2018-17196 Improper Input Validation in Apache Kafka High 8.8
• CVE-2025-27817 Apache Kafka Client: Arbitrary file read and SSRF vulnerability High 7.5
• CVE-2025-27819 Apache Kafka: Possible RCE/Denial of service attack via SASL JAAS JndiLoginModule configuration High 7.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as CLEANSTART-2026-BR61448, CLEANSTART-2026-HV53222, CLEANSTART-2026-KI11233, CLEANSTART-2026-VH87962, CLEANSTART-2026-WO81380, ECHO-9d81-4fd7-174c and 33 more.