The vulnerability in the Linux kernel's hwmon pmbus/adm1266 driver involved the adm1266_nvmem_read_blackbox() function looping over a record_count value obtained directly from byte 3 of the BLACKBOX_INFO response without validation. The destination buffer is sized for 32 records, but if the device reports a record_count greater than 32 (due to firmware bugs, bus corruption, or a non-responsive slave returning 0xff), the function would read beyond the allocated buffer, causing an out-of-bounds memory access. The fix introduced a cap on record_count at ADM1266_BLACKBOX_MAX_RECORDS (32) and returns an error (-EIO) if the value is larger, preventing the loop from exceeding buffer bounds.

This vulnerability could lead to out-of-bounds memory reads in the kernel, potentially causing kernel crashes or memory corruption. However, no known exploits in the wild have been reported. The impact is limited to systems using the affected hwmon pmbus/adm1266 driver and receiving malformed BLACKBOX_INFO responses.

A fix has been implemented in the Linux kernel to cap the record_count value before processing, preventing out-of-bounds reads. Users should apply the official kernel updates that include this patch once available. Patch status is not yet confirmed from the vendor advisory; check the Linux kernel release notes or vendor advisories for the specific fixed version and update accordingly.