CVE-2026-64085
Received Received - Intake

Buffer Overflow in Linux Kernel PMBus ADM1266 Driver

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: hwmon: (pmbus/adm1266) bounce blackbox records through a protocol-sized buffer adm1266_pmbus_block_xfer() copies the device-supplied block payload into the caller-provided buffer using the device-supplied length: memcpy(data_r, &msgs[1].buf[1], msgs[1].buf[0]); The helper does not know how large data_r is and trusts the device to return at most one record's worth of bytes. adm1266_nvmem_read_blackbox() violates that contract: it advances read_buff inside data->dev_mem in ADM1266_BLACKBOX_SIZE (64-byte) strides while the helper is willing to write up to ADM1266_PMBUS_BLOCK_MAX (255) bytes. A device that returns more than 64 bytes on the trailing record (read_buff offset 1984 in the 2048-byte dev_mem allocation) overflows dev_mem by up to 191 bytes before the post-call if (ret != ADM1266_BLACKBOX_SIZE) return -EIO; can reject the response. Contain the fix in the caller without changing the helper signature: read each record into a 255-byte local bounce buffer that matches the helper's maximum output, validate the returned length, and only then copy exactly ADM1266_BLACKBOX_SIZE bytes into the dev_mem slot.

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-64085
EUVD
EUVD-2026-45658

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is in the Linux kernel's hwmon subsystem, specifically in the pmbus/adm1266 driver. It involves a buffer overflow where a device can write more data than expected into a buffer. The issue occurs when reading blackbox records, where the device returns more bytes than the allocated buffer can handle, causing a 191-byte overflow.

Detection Guidance

This vulnerability is specific to the Linux kernel's hwmon subsystem, particularly the adm1266 driver. Detection requires checking the kernel version and whether the vulnerable code is present. Use commands like 'uname -a' to check the kernel version and 'modinfo adm1266' to verify if the driver is loaded.

Impact Analysis

This vulnerability could allow a malicious device to corrupt kernel memory, potentially leading to system crashes, privilege escalation, or arbitrary code execution. If exploited, it may compromise the integrity and stability of the affected system.

Compliance Impact

This vulnerability is a memory buffer overflow in the Linux kernel's hwmon subsystem, specifically in the pmbus/adm1266 driver. It does not directly relate to data privacy, security controls, or compliance requirements under standards like GDPR or HIPAA. The issue involves improper handling of device-supplied data in kernel memory, which could lead to system instability or crashes but does not inherently impact compliance with these regulations.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for CVE-2026-64085. If updating is not immediately possible, consider disabling the adm1266 driver module if it is not required.

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