An issue was discovered in IhisiSmm in Insyde InsydeH2O with kernel 5.0 through 5.5. IHISI subfunction execution may corrupt SMRAM. An attacker can pass an address in the RCX save state register that overlaps SMRAM, thereby coercing an IHISI subfunction handler to overwrite private SMRAM.

An issue was discovered in IhisiSmm in Insyde InsydeH2O with kernel 5.0 through 5.5. A malicious host OS can invoke an Insyde SMI handler with malformed arguments, resulting in memory corruption in SMM.