STMicroelectronics STSAFE-A1xx middleware before 3.3.7 allows MCU code execution if an adversary has the ability to read from and write to the I2C bus. This is caused by an StSafeA_ReceiveBytes buffer overflow in the X-CUBE-SAFEA1 Software Package for STSAFE-A sample applications (1.2.0), and thus can affect user-written code that was derived from a published sample application.