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.
Published: 2026-10-18
Score: 1.9 Low
EPSS: < 1% Very Low
KEV: No
Impact: Lost hardware‑updated dirty bits in huge page table entries
Action: Apply patch
AI Analysis

Impact

The vulnerability is a race condition in the Linux kernel’s damon_hugetlb_mkold() routine. When the kernel clears and restores a page table entry for a huge page, concurrent hardware updates to the same entry can be overwritten. The immediate effect is that hardware‑set dirty or accessed bits may be lost, leading to inconsistent page state and potentially delayed or missing writes back to storage. No crash or direct data disclosure occurs as described in the CVE data.

Affected Systems

All Linux kernel versions that implement damon_hugetlb_mkold() without the patch listed in the advisory are affected. This includes kernels from all manufacturers that ship this code path; any distribution kernel prior to a fix commit, regardless of version, remains vulnerable.

Risk and Exploitability

The CVSS score of 1.9 indicates a low severity flaw. The EPSS score is less than 1 %, suggesting a very low likelihood of exploitation. The flaw is not listed in CISA KEV. Exploitation would require kernel‑mode access and would affect only operations involving huge pages; no known attack vectors from user space are documented. Overall risk is considered low.

Generated by OpenCVE AI on October 20, 2026 at 13:29 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Update the Linux kernel to a version that includes the damon_hugetlb_mkold() fix or a newer patch level
  • If an immediate kernel upgrade is not possible, apply the patch from the advisory to the source tree and rebuild the kernel
  • If large pages are not required for your workloads, disable huge page support or limit the use of hugetlbfs to reduce exposure

Generated by OpenCVE AI on October 20, 2026 at 13:29 UTC.

Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4850-1 linux-6.12 security update
History

Wed, 21 Oct 2026 13:15:00 +0000


Tue, 20 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-821
References
Metrics threat_severity

None

cvssV3_1

{'score': 1.9, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:N'}

threat_severity

Low


Sun, 18 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
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.
Title mm/damon/vaddr: avoid hw-driven pte updates during damon_hugetlb_mkold()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-21T12:55:16.703Z

Reserved: 2026-09-25T10:25:14.353Z

Link: CVE-2026-98505

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-18T16:17:01.610

Modified: 2026-10-21T13:21:32.130

Link: CVE-2026-98505

cve-icon Redhat

Severity : Low

Publid Date: 2026-10-18T00:00:00Z

Links: CVE-2026-98505 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-20T13:30:06Z

Weaknesses
  • CWE-821

    Incorrect Synchronization