CVE-2026-93239
Received Received - Intake

Linux Kernel Page Table Walk Race Condition Fix

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: arm64: mm: Fix the lockless page-table walk in show_pte() show_pte() walks page tables locklessly and can run with interrupts enabled. A concurrent teardown can free a table page while it is being walked. It can also clear a parent entry after show_pte() checked it; the regular pXd_offset() helpers then reread the cleared entry and can derive a bogus lower-level pointer and fault again. Use the lockless offset helpers with the saved parent entries, as gup_fast() does, and pass the saved PMD to pte_offset_map(). For task page tables, arm64 selects MMU_GATHER_RCU_TABLE_FREE. Disable local interrupts around the walk to hold off RCU-deferred table frees and block the tlb_remove_table_sync_one() IPI until the walk is finished. Place the IRQ guard after the header print. This does not make the output a consistent snapshot, but prevents the task page-table walk from dereferencing a released table page or deriving a pointer from a different parent value.

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Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-25
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-93239
EUVD
EUVD-2026-86245

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is in the Linux kernel's arm64 memory management. It involves a race condition in the show_pte() function, which walks page tables without proper locking. A concurrent memory operation could free a page table while show_pte() is reading it, leading to incorrect pointer derivation and potential faults.

Detection Guidance

This vulnerability is specific to the Linux kernel's arm64 architecture and involves a race condition in page-table walking. Detection requires checking the kernel version and examining the affected code paths. Use commands like 'uname -a' to check the kernel version and 'dmesg' or 'journalctl' to look for related errors. However, no direct detection commands are provided in the context.

Impact Analysis

This flaw could cause system instability or crashes due to corrupted memory access. It may lead to unexpected behavior, data corruption, or denial of service if exploited. Systems running vulnerable Linux kernels are at risk.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it is a low-level memory management issue in the Linux kernel. Compliance impacts would depend on how the vulnerability is exploited in a specific system or application context, which is not described here.

Mitigation Strategies

Immediate mitigation involves updating the Linux kernel to a patched version that resolves the issue. Check your distribution's security advisories for the fixed kernel version and apply updates promptly. No specific commands or steps are provided in the context beyond kernel updates.

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