CVE-2026-90303

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

Published Sep 17, 2026 CVSS n/a EPSS < 1% KEV · Not listed

Description

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.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`6d021b724481fbb908eb29384898deb9f00dfe70`	affected	< ab14f07952adfe735d86a53518f8cd576dfd5892
`6d021b724481fbb908eb29384898deb9f00dfe70`	affected	< 07e4d5380f2a844ab7a1b440dde350caf561cbb0
`6d021b724481fbb908eb29384898deb9f00dfe70`	affected	< 2a14d7797a49a47bccd1a9327fd69da838dcb0dd
`6d021b724481fbb908eb29384898deb9f00dfe70`	affected	< 63e3c958a602d0896a101a897c2361878c266ca7
`6d021b724481fbb908eb29384898deb9f00dfe70`	affected	< 59bbf86d0ff9373bfa033ca123c1e924f09f1eba
`6d021b724481fbb908eb29384898deb9f00dfe70`	affected	< c71f9a56520b419e55d173052629f2324deb5549
`6d021b724481fbb908eb29384898deb9f00dfe70`	affected	< 720408d98d9fb3c91a12090436734c8c61f04545
`6d021b724481fbb908eb29384898deb9f00dfe70`	affected	< 1039bffd6ae9c75b42b7d148d6c1106134107b66

Linux

affected

Version	Status	Constraints
`4.0`	affected	—
`0`	unaffected	< 4.0
`5.10.270`	unaffected	≤ 5.10.*
`5.15.221`	unaffected	≤ 5.15.*
`6.1.188`	unaffected	≤ 6.1.*
`6.6.157`	unaffected	≤ 6.6.*
`6.12.110`	unaffected	≤ 6.12.*
`6.18.52`	unaffected	≤ 6.18.*
`7.2.6`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[6d021b724481fbb908eb29384898deb9f00dfe70,ab14f07952adfe735d86a53518f8cd576dfd5892)`	affected	code_commit	—
`[6d021b724481fbb908eb29384898deb9f00dfe70,07e4d5380f2a844ab7a1b440dde350caf561cbb0)`	affected	code_commit	—
`[6d021b724481fbb908eb29384898deb9f00dfe70,2a14d7797a49a47bccd1a9327fd69da838dcb0dd)`	affected	code_commit	—
`[6d021b724481fbb908eb29384898deb9f00dfe70,63e3c958a602d0896a101a897c2361878c266ca7)`	affected	code_commit	—
`[6d021b724481fbb908eb29384898deb9f00dfe70,59bbf86d0ff9373bfa033ca123c1e924f09f1eba)`	affected	code_commit	—
`[6d021b724481fbb908eb29384898deb9f00dfe70,c71f9a56520b419e55d173052629f2324deb5549)`	affected	code_commit	—
`[6d021b724481fbb908eb29384898deb9f00dfe70,720408d98d9fb3c91a12090436734c8c61f04545)`	affected	code_commit	—
`[6d021b724481fbb908eb29384898deb9f00dfe70,1039bffd6ae9c75b42b7d148d6c1106134107b66)`	affected	code_commit	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`4.0`	affected	generic	—
`[0,4.0)`	unaffected	generic	—
`[5.10.270,5.10.*]`	unaffected	generic	—
`[5.15.221,5.15.*]`	unaffected	generic	—
`[6.1.188,6.1.*]`	unaffected	generic	—
`[6.6.157,6.6.*]`	unaffected	generic	—
`[6.12.110,6.12.*]`	unaffected	generic	—
`[6.18.52,6.18.*]`	unaffected	generic	—
`[7.2.6,7.2.*]`	unaffected	generic	—
`[7.3-rc1,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4817-1	linux-6.12 security update
Debian DLA	DLA-4841-1	linux security update
Debian DSA	DSA-6528-1	linux security update
Ubuntu USN	USN-8961-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9019-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9020-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9022-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9023-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9024-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9025-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9026-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9029-1	Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN	USN-9039-1	Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN	USN-9040-1	Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN	USN-9066-1	Linux kernel (HWE) vulnerabilities
Ubuntu USN	USN-9091-1	Linux kernel (NVIDIA Tegra) vulnerabilities

Metrics

No CVSS v4.0

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.220% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/07e4d5380f2a844ab7a1b440dde350caf561cbb0
https://git.kernel.org/stable/c/1039bffd6ae9c75b42b7d148d6c1106134107b66
https://git.kernel.org/stable/c/2a14d7797a49a47bccd1a9327fd69da838dcb0dd
https://git.kernel.org/stable/c/59bbf86d0ff9373bfa033ca123c1e924f09f1eba
https://git.kernel.org/stable/c/63e3c958a602d0896a101a897c2361878c266ca7
https://git.kernel.org/stable/c/720408d98d9fb3c91a12090436734c8c61f04545
https://git.kernel.org/stable/c/ab14f07952adfe735d86a53518f8cd576dfd5892
https://git.kernel.org/stable/c/c71f9a56520b419e55d173052629f2324deb5549

History

Sep 17, 2026 4:30 PM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
Description		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.
Title		ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/07e4d5380f2a844ab7a1b440dde350caf561cbb0 https://git.kernel.org/stable/c/1039bffd6ae9c75b42b7d148d6c1106134107b66 https://git.kernel.org/stable/c/2a14d7797a49a47bccd1a9327fd69da838dcb0dd https://git.kernel.org/stable/c/59bbf86d0ff9373bfa033ca123c1e924f09f1eba https://git.kernel.org/stable/c/63e3c958a602d0896a101a897c2361878c266ca7 https://git.kernel.org/stable/c/720408d98d9fb3c91a12090436734c8c61f04545 https://git.kernel.org/stable/c/ab14f07952adfe735d86a53518f8cd576dfd5892 https://git.kernel.org/stable/c/c71f9a56520b419e55d173052629f2324deb5549