An issue was discovered in Kernel 5.x in Insyde InsydeH2O, affecting HddPassword. Software SMI services that use the Communicate() function of the EFI_SMM_COMMUNICATION_PROTOCOL do not check whether the address of the buffer is valid, which allows use of SMRAM, MMIO, or OS kernel addresses.

An issue was discovered in Insyde InsydeH2O with Kernel 5.0 before 05.08.42, Kernel 5.1 before 05.16.42, Kernel 5.2 before 05.26.42, Kernel 5.3 before 05.35.42, Kernel 5.4 before 05.42.51, and Kernel 5.5 before 05.50.51. An SMM memory corruption vulnerability in FvbServicesRuntimeDxe allows a possible attacker to write fixed or predictable data to SMRAM. Exploiting this issue could lead to escalating privileges to SMM.

A vulnerability exists in System Management Interrupt (SWSMI) handler of InsydeH2O UEFI Firmware code located in SWSMI handler that dereferences gRT (EFI_RUNTIME_SERVICES) pointer to call a GetVariable service, which is located outside of SMRAM. This can result in code execution in SMM (escalating privilege from ring 0 to ring -2).