The server in Circontrol Raption through 5.11.2 has a pre-authentication stack-based buffer overflow that can be exploited to gain run-time control of the device as root. The ocpp1.5 and pwrstudio binaries on the charging station do not use a number of common exploitation mitigations. In particular, there are no stack canaries and they do not use the Position Independent Executable (PIE) format.
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).