CVE-2026-97480
Received Received - Intake

NULL Pointer Dereference in Linux Kernel Serial 8250 Driver

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: tty: serial: 8250: protect against NULL uart->port.dev in register serial8250_register_8250_port() conditionally copies uart->port.dev from up->port.dev only when up->port.dev is non-NULL: if (up->port.dev) { uart->port.dev = up->port.dev; ... } So if both the existing uart slot and up have a NULL ->dev, uart->port.dev remains NULL. The very next ACPI companion check then dereferences it unconditionally: if (!has_acpi_companion(uart->port.dev)) { has_acpi_companion() reads dev->fwnode without a NULL guard (include/linux/acpi.h), so this NULL-derefs the kernel for the remaining no-dev case rather than just skipping the mctrl_gpio_init() initialisation as intended. smatch flags the inconsistency: drivers/tty/serial/8250/8250_core.c:767 serial8250_register_8250_port() error: 'uart->port.dev' could be null (see line 719) Guard the call with a NULL check so register continues to work for callers that legitimately have no parent device (legacy non-OF/non-ACPI registrations). No functional change for callers that pass a non-NULL ->dev.

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Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-24
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-97480
EUVD
EUVD-2026-86078

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 is a NULL pointer dereference vulnerability in the Linux kernel's serial port driver. It occurs when the uart->port.dev field is NULL and the code attempts to check for an ACPI companion without first verifying if the device pointer is valid. This leads to a kernel crash.

Detection Guidance

This vulnerability is specific to the Linux kernel's serial driver and does not have network-based detection methods. It requires kernel-level inspection. Check if your kernel version includes the vulnerable code path by examining the serial8250_register_8250_port function in the 8250_core.c file. Look for missing NULL checks on uart->port.dev before calling has_acpi_companion().

Impact Analysis

If exploited, this vulnerability could cause a system crash or kernel panic, leading to denial of service. Systems relying on serial ports for critical functions may become unresponsive.

Mitigation Strategies

Apply the kernel patch that adds a NULL check for uart->port.dev before calling has_acpi_companion(). Update to a kernel version that includes this fix. If immediate patching is not possible, avoid using legacy non-OF/non-ACPI serial device registrations until the fix is applied.

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