A flaw was found in the Apache Commons BeanUtils, where the class property in PropertyUtilsBean is not suppressed by default. This flaw allows an attacker to access the classloader.
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.