CVE-2026-89740

Received Received - Intake

Race Condition in Linux Kernel Serial Driver

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: serial: imx: serialize imx_uart_ports[] lifetime imx_uart_probe() publishes its devm-allocated port in imx_uart_ports[] before uart_add_one_port() because console setup uses the table. The entry is not cleared when adding the port fails or after removal, leaving a dangling pointer. A sibling probe can register the shared console through that stale entry. This was reproduced under KASAN on QEMU mcimx6ul-evk by unbinding a sibling UART, unbinding the console UART and rebinding the sibling. Keep the entry valid through uart_remove_one_port(), then clear it. Protect port addition and removal together with their table updates so sibling operations cannot interleave. Reject an occupied slot rather than clobbering an active port during a duplicate-line probe.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-09-11

Last Modified

2026-09-11

Generated

2026-09-12

AI Q&A

2026-09-12

EPSS Evaluated

N/A

NVD

CVE-2026-89740

EUVD

EUVD-2026-76652

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a race condition in the imx UART serial driver. The issue occurs when the imx_uart_probe function adds a port to the imx_uart_ports array before the port is fully initialized. If the port addition fails or is removed, the array entry is not cleared, leaving a dangling pointer. This can allow a sibling probe to register a shared console through the stale entry, potentially causing system instability or crashes.

Detection Guidance

This vulnerability is specific to the Linux kernel's imx UART driver and requires kernel-level inspection. Detection involves checking kernel logs for UART-related errors or crashes, particularly during probe/removal cycles. Use dmesg | grep -i uart or journalctl -k | grep -i uart to review kernel messages. No network-specific detection commands are applicable.

Impact Analysis

This vulnerability could lead to system crashes, data corruption, or unauthorized access if exploited. It may cause kernel panics or unexpected behavior in systems using the imx UART serial driver, particularly in embedded Linux devices. Attackers could potentially trigger the race condition to gain control over the console or disrupt serial communication.

Mitigation Strategies

Apply the latest Linux kernel patches from your distribution to resolve the imx UART driver issue. If immediate patching isn't possible, avoid unbinding UART devices or console UARTs to prevent triggering the race condition. Monitor kernel updates closely for fixes.

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