---
id: CVE-2026-90303
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults

  When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
  a user fault may trigger show_…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults

  When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
  a user fault may trigger show_…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 6d021b724481fbb908eb29384898deb9f00dfe70 <
    ab14f07952adfe735d86a53518f8cd576dfd5892
  - >-
    Linux >= 6d021b724481fbb908eb29384898deb9f00dfe70 <
    07e4d5380f2a844ab7a1b440dde350caf561cbb0
  - >-
    Linux >= 6d021b724481fbb908eb29384898deb9f00dfe70 <
    2a14d7797a49a47bccd1a9327fd69da838dcb0dd
  - >-
    Linux >= 6d021b724481fbb908eb29384898deb9f00dfe70 <
    63e3c958a602d0896a101a897c2361878c266ca7
  - >-
    Linux >= 6d021b724481fbb908eb29384898deb9f00dfe70 <
    59bbf86d0ff9373bfa033ca123c1e924f09f1eba
  - >-
    Linux >= 6d021b724481fbb908eb29384898deb9f00dfe70 <
    c71f9a56520b419e55d173052629f2324deb5549
  - >-
    Linux >= 6d021b724481fbb908eb29384898deb9f00dfe70 <
    720408d98d9fb3c91a12090436734c8c61f04545
  - >-
    Linux >= 6d021b724481fbb908eb29384898deb9f00dfe70 <
    1039bffd6ae9c75b42b7d148d6c1106134107b66
  - Linux 4.0
published: '2026-09-17'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:17:27.887'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90303'
references:
  - url: 'https://git.kernel.org/stable/c/07e4d5380f2a844ab7a1b440dde350caf561cbb0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/1039bffd6ae9c75b42b7d148d6c1106134107b66'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2a14d7797a49a47bccd1a9327fd69da838dcb0dd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/59bbf86d0ff9373bfa033ca123c1e924f09f1eba'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/63e3c958a602d0896a101a897c2361878c266ca7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/720408d98d9fb3c91a12090436734c8c61f04545'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ab14f07952adfe735d86a53518f8cd576dfd5892'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c71f9a56520b419e55d173052629f2324deb5549'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-17T16:21:47.828Z'
epss: 0.0021
epssPercentile: 0.11553
---

## Overview

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

ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults

When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
a user fault may trigger show_pte() without any lock.
If another thread in the same process concurrently calls munmap(),
the page table pages may be freed while show_pte() is still traversing
them, causing a use-after-free in show_pte().

If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table
of PMD are freed when show_pte() is running.

Acquire mmap_write_lock() around show_pte() for user faults to fix the
contention.

For user faults, additionally restrict that show_pte() is called only
when the addr is a user-space address (addr < TASK_SIZE). This is because
the lock of tsk->mm only protects the virtual memory of user address space,
furthermore, dumping the page tables of a kernel-space address for user
faults is unnecessary and may have security implications.

Keep everything unchanged for kernel faults, because the kernel is
already in the "oops" state, acquiring a lock may risk a deadlock.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.