---
id: CVE-2026-89721
title: >-
  kernel: phy: rockchip-samsung-dcphy: fix out-of-range max_register
  (CVE-2026-89721)
summary: >-
  A flaw was found in the Linux kernel's `phy: rockchip-samsung-dcphy`
  component. A local attacker with access to the `regmap debugfs` interface
  could trigger an out-of-bounds read by attempting to dump registers. This
  occurs because the `ma…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: vendor
cwe: CWE-125
vendor: Red Hat
product: Red Hat OpenShift Container Platform 4
affected:
  - openshift_container_platform 4
published: '2026-09-11'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T17:24:41+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89721.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89721.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89721'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532300'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89721'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89721'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89721.mbox
  - url: 'https://git.kernel.org/stable/c/14afe18655c0951f4f85898f761bf92264e65ccd'
  - url: 'https://git.kernel.org/stable/c/4486e75ba647bd8b98fc1f053101b40caceeed4b'
  - url: 'https://git.kernel.org/stable/c/c1a62f9dcf531d56c56da2e4435386b6d264c69f'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
epss: 0.00206
epssPercentile: 0.0949
ingestedAt: '2026-09-14T11:11:19.885Z'
---

## Overview

A flaw was found in the Linux kernel's `phy: rockchip-samsung-dcphy` component. A local attacker with access to the `regmap debugfs` interface could trigger an out-of-bounds read by attempting to dump registers. This occurs because the `max_register` value is incorrectly set, causing the system to read beyond the allocated memory region. Successful exploitation leads to a kernel crash (oops) and a subsequent deadlock of physical layer (PHY) operations, resulting in a denial of service.

## Vendor advisories

- **Red Hat VEX** · Moderate · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89721.json)

**kernel: phy: rockchip-samsung-dcphy: fix out-of-range max_register** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-21.

Not affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4

## Remediation

Refer to the advisory for fix availability.