A memory corruption vulnerability in SdHost and SdMmcDevice in Insyde InsydeH2O kernel 5.2 before 05.29.09, kernel 5.3 before 05.38.09, kernel 5.4 before 05.46.09, kernel 5.5 before 05.54.09, and kernel 5.6 before 05.61.09 could lead to escalating privileges in SMM.
The product obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer.
An attacker can supply a pointer for memory locations that the product is not expecting. If the pointer is dereferenced for a write operation, the attack might allow modification of critical state variables, cause a crash, or execute code. If the dereferencing operation is for a read, then the attack might allow reading of sensitive data, cause a crash, or set a variable to an unexpected value (since the value will be read from an unexpected memory location). There are several variants of this weakness, including but not necessarily limited to: