CVE-2026-64083
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) reject short block-read responses in the GPIO accessors adm1266_gpio_get() and adm1266_gpio_get_multiple() both compose the pin-status word as pins_status = read_buf[0] + (read_buf[1] << 8); right after i2c_smbus_read_block_data(), guarding only against an error return. A well-behaved device returns 2 bytes for GPIO_STATUS/PDIO_STATUS, but the helper happily reports a 0- or 1-byte response too. If the device returns 0 bytes, both read_buf slots are uninitialized stack memory; if it returns 1 byte, read_buf[1] is. The composed value then flows through set_bit() into the caller's *bits in adm1266_gpio_get_multiple(), or into the return value of adm1266_gpio_get(), and ends up in userspace via gpiolib (sysfs and the char-dev ioctls). That leaks a few bits of kernel stack per request on any device whose firmware glitch, bus error, or hostile slave produces a short block-read response. Add the missing length check to both call sites and surface a short response as -EIO.

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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-2026-64083
EUVD
EUVD-2026-45656

Affected Vendors & Products

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

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel affects the hwmon subsystem, specifically the pmbus/adm1266 driver. It involves improper handling of short block-read responses in GPIO accessor functions. The functions adm1266_gpio_get() and adm1266_gpio_get_multiple() read GPIO status from a device but fail to validate the response length properly. A short response can lead to uninitialized stack memory being used, leaking kernel data to userspace.

Detection Guidance

This vulnerability affects the Linux kernel's hwmon subsystem, specifically the adm1266 driver. Detection requires checking the kernel version and verifying if the vulnerable code paths are present. Use uname -a to check the kernel version and grep for the adm1266 driver in the kernel source or loaded modules.

Impact Analysis

This vulnerability could allow an attacker with access to the affected system to read small amounts of kernel stack memory. This might expose sensitive information such as kernel addresses or other internal data. The impact is limited to information disclosure and requires either a hardware glitch, bus error, or a compromised device firmware.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It involves a kernel stack memory leak in the Linux hwmon subsystem due to improper handling of short block-read responses in GPIO accessors. The impact is limited to potential information exposure in kernel memory, not regulatory compliance issues.

Mitigation Strategies

Apply the latest kernel update that includes the fix for CVE-2026-64083. If an update is not immediately available, consider disabling the adm1266 driver module if it is not required. Monitor vendor advisories for patches.

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