CVE-2025-27818 Apache Kafka: Possible RCE attack via SASL JAAS LdapLoginModule configuration

What is CVE-2025-27818?

CVE-2025-27818 is a high-severity unsafe deserialization vulnerability in Apache Kafka, published on 10 Jun 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A possible security vulnerability has been identified in Apache Kafka. This requires access to a alterConfig to the cluster resource, or Kafka Connect worker, and the ability to create/modify connectors on it with an arbitrary Kafka client SASL JAAS config and a SASL-based security protocol, which has been possible on Kafka clusters since Apache Kafka 2.0.0 (Kafka Connect 2.3.0). When configuring the broker via config file or AlterConfig command, or connector via the Kafka Kafka Connect REST API, an authenticated operator can set the `sasl.jaas.config` property for any of the connector's Kafka clients to "com.sun.security.auth.module.LdapLoginModule", which can be done via the `producer.override.sasl.jaas.config`, `consumer.override.sasl.jaas.config`, or `admin.override.sasl.jaas.config` properties. This will allow the server to connect to the attacker's LDAP server and deserialize the LDAP response, which the attacker can use to execute java deserialization gadget chains on the Kafka connect server. Attacker can cause unrestricted deserialization of untrusted data (or) RCE vulnerability when there are gadgets in the classpath.

Since Apache Kafka 3.0.0, users are allowed to specify these properties in connector configurations for Kafka Connect clusters running with out-of-the-box configurations. Before Apache Kafka 3.0.0, users may not specify these properties unless the Kafka Connect cluster has been reconfigured with a connector client override policy that permits them.

Since Apache Kafka 3.9.1/4.0.0, we have added a system property ("-Dorg.apache.kafka.disallowed.login.modules") to disable the problematic login modules usage in SASL JAAS configuration. Also by default "com.sun.security.auth.module.JndiLoginModule,com.sun.security.auth.module.LdapLoginModule" are disabled in Apache Kafka Connect 3.9.1/4.0.0.

We advise the Kafka users to validate connector configurations and only allow trusted LDAP configurations. Also examine connector dependencies for vulnerable versions and either upgrade their connectors, upgrading that specific dependency, or removing the connectors as options for remediation. Finally, in addition to leveraging the "org.apache.kafka.disallowed.login.modules" system property, Kafka Connect users can also implement their own connector client config override policy, which can be used to control which Kafka client properties can be overridden directly in a connector config and which cannot.

Weakness: CWE-502

Which versions are affected by CVE-2025-27818?

7 open source packages ship an affected version, including org.apache.kafka:kafka_2.11, kafka and org.apache.kafka:kafka_2.12. It affects 1 product.

Products include Apache Kafka.

How do I fix CVE-2025-27818?

Change a configuration setting.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2025-27818 being exploited?

There is no known exploitation of CVE-2025-27818 in the wild and no public exploit code.

Other vulnerabilities in Apache Kafka

• CVE-2026-33557 Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication Critical 9.1
• CVE-2018-17196 Improper Input Validation in Apache Kafka High 8.8
• CVE-2026-35554 Apache Kafka Clients: Kafka Producer Message Corruption and Misrouting via Buffer Pool Race Condition High 8.7
• 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 BIT-kafka-2025-27818, ECHO-6971-a227-7838, GHSA-76qp-h5mr-frr4, MINI-5645-9xq5-xhrr, MINI-65m6-qc5c-22q4, MINI-c47f-c47w-gqpv and 4 more.