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 Commons Beanutils 1.9.2, a special BeanIntrospector class was added which allows suppressing the ability for an attacker to access the classloader via the class property available on all Java objects. We, however were not using this by default characteristic of the PropertyUtilsBean.