A buffer overflow flaw in the Service Processor mailbox interface allows an attacker with authenticated service-level access to craft a message that reads or writes arbitrary Hostboot memory. This can compromise the host firmware boot stack and any hypervisor subsequently loaded, resulting in confidentiality, integrity, and availability loss for the managed system.

The flaw affects IBM PowerVM Hypervisor firmware versions FW1060.00 through FW1060.81 on Power 10 devices including the IBM Power System S1022 (9105‑22A), S1024 (9105‑42A), S1022s (9105‑22B), S1014 (9105‑41B), L1022 (9786‑22H), L1024 (9786‑42H), E1050 (9043‑MRX), and S1012 (9028‑21B). All of these systems must upgrade to FW1060.82 or later to remediate the vulnerability.

The CVSS score of 8.2 indicates a high severity. EPSS data is not available and the vulnerability is not present in the CISA KEV catalog. Based on the description, it is inferred that attackers must first obtain authenticated service-level access to the Service Processor; the mailbox interface permits a specially crafted message to cause the buffer overflow. The likely attack vector is network or local access to the service processor.