A security vulnerability has been identified in Apache Kafka. It affects all releases since 2.8.0. The vulnerability allows malicious unauthenticated clients to allocate large amounts of memory on brokers. This can lead to brokers hitting OutOfMemoryException and causing denial of service. Example scenarios: - Kafka cluster without authentication: Any clients able to establish a network connection to a broker can trigger the issue. - Kafka cluster with SASL authentication: Any clients able to establish a network connection to a broker, without the need for valid SASL credentials, can trigger the issue. - Kafka cluster with TLS authentication: Only clients able to successfully authenticate via TLS can trigger the issue. We advise the users to upgrade the Kafka installations to one of the 3.2.3, 3.1.2, 3.0.2, 2.8.2 versions.

Some components in Apache Kafka use `Arrays.equals` to validate a password or key, which is vulnerable to timing attacks that make brute force attacks for such credentials more likely to be successful. Users should upgrade to 2.8.1 or higher, or 3.0.0 or higher where this vulnerability has been fixed. The affected versions include Apache Kafka 2.0.0, 2.0.1, 2.1.0, 2.1.1, 2.2.0, 2.2.1, 2.2.2, 2.3.0, 2.3.1, 2.4.0, 2.4.1, 2.5.0, 2.5.1, 2.6.0, 2.6.1, 2.6.2, 2.7.0, 2.7.1, and 2.8.0.

In Eclipse Jetty version 9.4.0.RC0 to 9.4.34.v20201102, 10.0.0.alpha0 to 10.0.0.beta2, and 11.0.0.alpha0 to 11.0.0.beta2, if GZIP request body inflation is enabled and requests from different clients are multiplexed onto a single connection, and if an attacker can send a request with a body that is received entirely but not consumed by the application, then a subsequent request on the same connection will see that body prepended to its body. The attacker will not see any data but may inject data into the body of the subsequent request.

When Connect workers in Apache Kafka 2.0.0, 2.0.1, 2.1.0, 2.1.1, 2.2.0, 2.2.1, or 2.3.0 are configured with one or more config providers, and a connector is created/updated on that Connect cluster to use an externalized secret variable in a substring of a connector configuration property value, then any client can issue a request to the same Connect cluster to obtain the connector's task configuration and the response will contain the plaintext secret rather than the externalized secrets variables.

In Apache Kafka versions between 0.11.0.0 and 2.1.0, it is possible to manually craft a Produce request which bypasses transaction/idempotent ACL validation. Only authenticated clients with Write permission on the respective topics are able to exploit this vulnerability. Users should upgrade to 2.1.1 or later where this vulnerability has been fixed.

In Apache Kafka 0.9.0.0 to 0.9.0.1, 0.10.0.0 to 0.10.2.1, 0.11.0.0 to 0.11.0.2, and 1.0.0, authenticated Kafka users may perform action reserved for the Broker via a manually created fetch request interfering with data replication, resulting in data loss.

In Apache Kafka 0.10.0.0 to 0.10.2.1 and 0.11.0.0 to 0.11.0.1, authenticated Kafka clients may use impersonation via a manually crafted protocol message with SASL/PLAIN or SASL/SCRAM authentication when using the built-in PLAIN or SCRAM server implementations in Apache Kafka.