Improper access control in steve-community steve

Summary

SteVe is an open-source EV charging station management system. In versions up to and including 3.11.0, when a charger sends a StopTransaction message, SteVe looks up the transaction solely by transactionId (a sequential integer starting from 1) without verifying that the requesting charger matches the charger that originally started the transaction. Any authenticated charger can terminate any other charger’s active session across the entire network. The root cause is in OcppServerRepositoryImpl.getTransaction() which queries only by transactionId with no chargeBoxId ownership check. The validator checks that the transaction exists and is not already stopped but never verifies identity. As an attacker controlling a single registered charger I could enumerate sequential transaction IDs and send StopTransaction messages targeting active sessions on every other charger on the network simultaneously. Combined with FINDING-014 (unauthenticated SOAP endpoints), no registered charger is even required — the attack is executable with a single curl command requiring only a known chargeBoxId. Commit 7f169c6c5b36a9c458ec41ce8af581972e5c724e contains a fix for the issue.