The openUBMC device-management process parses PLDM-over-MCTP and NCSI-over-MCTP responses from on-bus devices, and three response parsers in the shared transport libraries subtract a fixed header or reserved-field size from a device-supplied response length without a lower-bound check. An undersized response wraps the unsigned length difference to a very large value, and the parser then reads far past the response buffer. The affected code sits in the base (non-vendor) PLDM control class and the Huawei NCSI driver, so it is reachable for any PLDM endpoint or Huawei NIC on the internal management bus, unlike the vendor-specific wangxun parser tracked separately.