CVE-2026-98505
Received Received - Intake

Memory Corruption in Linux Kernel via Parallel PTE Updates

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: mm/damon/vaddr: avoid hw-driven pte updates during damon_hugetlb_mkold() damon_hugetlb_mkold() reads the page table entry into a local variable, unsets the accessed bit in the variable, and updates the page table entry with the updated variable value. If hardware updates the same page table entry in parallel, the hw updates could be lost. For example, hardware-updated dirty bits might be lost. Avoid the parallel updates by clearing the page table entry when reading it together, using huge_ptep_get_and_clear(). If a parallel write to the memory is made after the clearing, the hw will see the page table entry is cleared, trigger page fault and wait until it is handled. The page fault handling will wait for damon_hugetlb_mkold() due to the page table lock. Because hugetlbfs is an in-memory file system and hugetlb pages cannot be reclaimed, no critical issue is expected to my best knowledge. But definitely this is a nasty bug that should be fixed sooner rather than later. The issue was discovered [1] by Sashiko.

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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-19
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98505
EUVD
EUVD-2026-103745

Affected Vendors & Products

Showing 5 associated CPEs
Vendor Product Version / Range
Linux Linux 49f4203aae06ba9d67b500c90339b262b0a52637
Linux Linux 49f4203aae06ba9d67b500c90339b262b0a52637
Linux Linux 49f4203aae06ba9d67b500c90339b262b0a52637
Linux Linux 49f4203aae06ba9d67b500c90339b262b0a52637
Linux Linux 5.17

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Exploitability

CWE
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a race condition in the DAMON memory management subsystem. The function damon_hugetlb_mkold() reads a page table entry, modifies it to clear the accessed bit, and writes it back. If hardware updates the same entry concurrently, those changes could be lost, potentially causing issues with dirty bit tracking in hugetlbfs pages.

Detection Guidance

This vulnerability is specific to the Linux kernel's DAMON subsystem and hugetlbfs. Detection requires checking kernel logs for related errors or examining the DAMON subsystem configuration. No direct commands are provided in the context to detect this issue.

Impact Analysis

The impact is limited because hugetlbfs pages cannot be reclaimed, reducing critical risk. However, it could cause subtle memory management issues like incorrect dirty bit tracking, leading to inefficient page handling or unnecessary page faults. Users might experience minor performance degradation or unexpected behavior in memory-intensive applications.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It involves a race condition in the Linux kernel's memory management for hugetlbfs pages, which is unlikely to cause data corruption or unauthorized access. No evidence suggests it impacts data protection or privacy requirements.

Mitigation Strategies

Apply the Linux kernel patch that resolves this issue. Update to a kernel version that includes the fix for mm/damon/vaddr.c. Monitor kernel updates from your distribution vendor for the patched version.

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