Unvalidated pin index in GPIO syscall handlers allows out-of-bounds kernel writes from user mode

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-82961
StatePUBLISHED
Assignerzephyr
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-28 17:18:43 UTC
Updated2026-10-28 17:18:43 UTC
DescriptionThe GPIO syscall handlers in drivers/gpio/gpio_handlers.c did not validate the pin argument supplied by a user-mode caller. z_vrfy_gpio_pin_configure(), z_vrfy_gpio_pin_get_config() and z_vrfy_gpio_pin_interrupt_configure() verified only the device object (K_SYSCALL_DRIVER_GPIO() / K_SYSCALL_OBJ()) and then passed the caller-supplied gpio_pin_t straight through to z_impl_gpio_pin_*() and on to the driver. The only pin check in include/zephyr/drivers/gpio.h was __ASSERT(gpio_port_pin_is_supported(cfg->port_pin_mask, pin), ...), which compiles to nothing unless CONFIG_ASSERT is enabled, so in a production build no check existed at all. GPIO drivers use pin as a shift count and as an array index on the documented assumption that it is a pin the controller supports. On STM32, for example, gpio_stm32_pin_interrupt_configure() turns pin into an EXTI line and stm32_gpio_intc_set_irq_callback() writes data->cb[line_num].cb and data->cb[line_num].data into a NUM_EXTI_LINES-entry array (default 16) in drivers/interrupt_controller/intc_gpio_stm32.c, guarded only by a compiled-out __ASSERT_NO_MSG(); the same function then reads exti_irq_table[line_num] and calls irq_enable() on the result. Other controllers index fixed-size per-pin configuration tables the same way — drivers/gpio/gpio_ite_it8xxx2_v2.c reads an MMIO base pointer out of wuc_base[8] with the caller's pin and performs a read-modify-write through it. The issue is reachable only in builds with CONFIG_USERSPACE=y (the file is compiled under that symbol), by a user-mode thread that has been granted access to a GPIO device object. Such a grant is intended to authorize control of that port's pins; the missing validation instead lets the thread drive a supervisor-mode out-of-bounds write of a function pointer and an associated void * past a kernel .bss array, and out-of-bounds reads that feed irq_enable() and MMIO accesses — an escape from the user-mode sandbox that can lead to kernel memory corruption, arbitrary code execution, or a crash. The fix validates pin against the controller's gpio_driver_config.port_pin_mask with gpio_port_pin_is_supported() in every pin-taking z_vrfy_ handler and returns -EINVAL otherwise, complemented by an unconditional pin >= GPIO_MAX_PINS_PER_PORT range check added to the shared z_impl_gpio_pin_*() inlines.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001290000 probability, percentile 0.025350000 (date 2026-10-29)

Problem Types: CWE-787 | CWE-787 bounds

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Zephyrproject Zephyr affected 2.2.0 4.4.2 semver Not specified

References

ReferenceSourceLinkTags
github.com/zephyrproject-rtos/zephyr/commit/d145faab7e3a8cea62a8fd7ed5f3... [email protected] github.com
github.com/zephyrproject-rtos/zephyr/commit/d28a05d5de4420f27ba3de7b9e44... [email protected] github.com
github.com/zephyrproject-rtos/zephyr/commit/c9641fa5bfec44892e0cf2d84f78... [email protected] github.com
github.com/zephyrproject-rtos/zephyr/commit/020e83e06b35e98a4a3c2354f67e... [email protected] github.com
github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-4f2x-8qw8-... [email protected] github.com
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