In Eclipse OpenJ9 versions prior to 0.63.0, the JITServer component fails to perform cross-field validation on attacker-controlled _size, _paddingSize, and _dataOffset fields during DataDescriptor message deserialization. An unauthenticated remote attacker can send a crafted network payload that triggers an unsigned integer underflow in DataDescriptor::getPayloadSize() and DataDescriptor::getNextDescriptor(). This results in an out-of-bounds heap read and an immediate process crash (SIGSEGV), causing a denial of service.