A memory corruption vulnerability in HddPassword 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.
An issue was discovered in IhisiSmm in Insyde InsydeH2O with kernel 5.0 through 5.5. It is possible to write to an attacker-controlled address. An attacker could invoke an SMI handler with a malformed pointer in RCX that overlaps SMRAM, resulting in SMM memory corruption.