---
id: "CVE-2026-98695"
kind: "vulnerability"
aliases: ["CVE-2026-98695"]
title: "Linux kernel USB serial: ioctl race with hangup causes NULL dereference"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "linux", "usb-serial"]
not_affected_if: []
published_at: "2026-10-18T16:17:22+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:18:59+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98695", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel USB serial: ioctl race with hangup causes NULL dereference

A race between tty ioctls and device hangup in the Linux kernel USB serial driver lets an ioctl call into a driver for a device that is already disconnected. The sources describe this as a NULL-pointer dereference when a device is removed during lengthy break signalling.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98695

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

USB: serial: fix ioctl hangup race

The tty ioctls can race with hangup and end up calling into a tty driver
for a device that is already gone or powered down.

Serialise the callbacks using the tty port mutex and add the missing
checks to make sure the port has not been hung up before accessing port
driver data or hardware.

This specifically avoids dereferencing a NULL-pointer if a device is
disconnected during lengthy break signalling.

Note that TIOCGICOUNT and TIOCMIWAIT do not access port driver data or
hardware and are therefore not affected by the race.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_