Shearwater SecurEnvoy SecurAccess Enrol before 9.4.515 allows authentication through only a six-digit TOTP code (skipping a password check) if an HTTP POST request contains a SESSION parameter.
https://securenvoy.com/wp-content/uploads/2025/03/Release-Notes-9.4.515.pdf
https://reserge.org/probabilistically-breaking-securenvoy-totp/