An application that includes BeanShell on the classpath may be vulnerable if another part of the application uses Java serialization or XStream to deserialize data from an untrusted source.

A vulnerable application could be exploited for remote code execution, including executing arbitrary shell commands.

External references:

https://github.com/beanshell/beanshell/releases/tag/2.0b6

Upstream patches:

https://github.com/beanshell/beanshell/commit/7c68fde2d6fc65e362f20863d868c112a90a9b49

https://github.com/beanshell/beanshell/commit/1ccc66bb693d4e46a34a904db8eeff07808d2ced