CVE-2026-64135
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) widen blackbox-info buffer to I2C_SMBUS_BLOCK_MAX adm1266_nvmem_read_blackbox() declares a 5-byte stack buffer and passes it to i2c_smbus_read_block_data() to retrieve the 4-byte BLACKBOX_INFO response. i2c_smbus_read_block_data() does not honour caller buffer sizes -- it memcpy()s data.block[0] bytes from the SMBus transaction (where data.block[0] is the length byte returned by the slave device, up to I2C_SMBUS_BLOCK_MAX = 32): memcpy(values, &data.block[1], data.block[0]); If the device returns any block length above 5, the call overflows the caller's 5-byte stack buffer before the post-call if (ret != 4) return -EIO; check has a chance to reject the response. Widen the local buffer to I2C_SMBUS_BLOCK_MAX so the helper has room for any well-formed SMBus block response, matching the convention used by the other i2c_smbus_read_block_data() callers in this driver.

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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-2026-64135
EUVD
EUVD-2026-45820

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
linux_kernel linux_kernel *
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 a buffer overflow issue in the Linux kernel's hwmon subsystem, specifically in the pmbus/adm1266 driver. A 5-byte stack buffer is used to read a 4-byte BLACKBOX_INFO response from an SMBus device. The function i2c_smbus_read_block_data() can return up to 32 bytes, causing a buffer overflow if the device returns more than 5 bytes. The fix widens the buffer to I2C_SMBUS_BLOCK_MAX to prevent overflow.

Detection Guidance

This vulnerability is specific to the Linux kernel's hwmon subsystem for the adm1266 PMBus device. Detection requires checking the kernel version and the presence of the affected driver. Use commands like 'uname -a' to check kernel version and 'lsmod | grep adm1266' to verify if the driver is loaded.

Impact Analysis

This vulnerability could allow an attacker with access to the SMBus interface to cause a buffer overflow, potentially leading to memory corruption, crashes, or arbitrary code execution on the affected system. It may also enable privilege escalation if exploited.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a low-level buffer overflow in the Linux kernel's hwmon subsystem related to SMBus communication. Compliance impacts would only occur if exploitation led to system compromise, data breaches, or unauthorized access, which is not described in the provided context.

Mitigation Strategies

Update the Linux kernel to a patched version where this issue is resolved. Monitor vendor advisories for kernel updates and apply them promptly. If using a custom kernel, ensure the adm1266 driver is updated to handle block data safely.

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