CVE-2025-27819

In CVE-2023-25194, we announced the RCE/Denial of service attack via SASL JAAS JndiLoginModule configuration in Kafka Connect API. But not only Kafka Connect API is vulnerable to this attack, the Apache Kafka brokers also have this vulnerability. To exploit this vulnerability, the attacker needs to be able to connect to the Kafka cluster and have the AlterConfigs permission on the cluster resource.

Since Apache Kafka 3.4.0, 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" is disabled in Apache Kafka 3.4.0, and "com.sun.security.auth.module.JndiLoginModule,com.sun.security.auth.module.LdapLoginModule" is disabled by default in in Apache Kafka 3.9.1/4.0.0

Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.

CVE-2025-27819 has a CVSS score of 8.8 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.4.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-27819? CVE-2025-27819 is a high-severity insecure deserialization vulnerability in org.apache.kafka:kafka_2.10 (maven), affecting versions < 3.4.0. It is fixed in 3.4.0. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
2. How severe is CVE-2025-27819? CVE-2025-27819 has a CVSS score of 8.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2025-27819?
   • org.apache.kafka:kafka_2.10 (maven) (versions < 3.4.0)
   • org.apache.kafka:kafka_2.11 (maven) (versions < 3.4.0)
   • org.apache.kafka:kafka_2.12 (maven) (versions < 3.4.0)
   • org.apache.kafka:kafka_2.13 (maven) (versions < 3.4.0)
   • org.apache.kafka:kafka_2.8.0 (maven) (versions < 3.4.0)
   • org.apache.kafka:kafka_2.8.2 (maven) (versions < 3.4.0)
   • org.apache.kafka:kafka_2.9.1 (maven) (versions < 3.4.0)
   • org.apache.kafka:kafka_2.9.2 (maven) (versions < 3.4.0)
4. Is there a fix for CVE-2025-27819? Yes. CVE-2025-27819 is fixed in 3.4.0. Upgrade to this version or later.
5. Is CVE-2025-27819 exploitable, and should I be worried? Whether CVE-2025-27819 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-27819 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-27819?
   • Upgrade org.apache.kafka:kafka_2.12 to 3.4.0 or later
   • Upgrade org.apache.kafka:kafka_2.13 to 3.4.0 or later