The rend_service_intro_established function in or/rendservice.c in Tor before 0.2.8.15 0.2.9.x before 0.2.9.12 0.3.0.x before 0.3.0.11 0.3.1.x before 0.3.1.7 and 0.3.2.x before 0.3.2.1-alpha when SafeLogging is disabled allows attackers to obtain sensitive information by leveraging access to the log files of a hidden service because uninitialized stack data is included in an error message about construction of an introduction point circuit.