ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. In versions 5.2.6, 5.3.5, 5.4.4, 5.5.4, and 6.0, a heap buffer overflow exists in the Security Scheme 2 (SRP6a) session-setup path of the protocomm component. The first-phase handler (handle_session_command0() in components/protocomm/src/security/security2.c) trusts the length of a client-supplied protobuf field for the SRP6a username and copies it into a buffer whose size is derived from a narrower destination type. The resulting truncation-versus-copy asymmetry corrupts the heap when an oversized value is supplied. This issue has been patched in versions 5.2.7, 5.3.6, 5.4.5, 5.5.5, and 6.0.1.