CVE-2025-38084

Medium

In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: unshare page tables during VMA split, not before Currently, __split_vma() triggers hugetlb page table unsharing through vm_ops->may_split(). This happens before the VMA lock and rmap locks are taken - which is too early, it allows racing VMA-locked page faults in our process and racing rmap walks from other processes to cause page tables to be shared again before we actually perform the split. Fix it by explicitly calling into the hugetlb unshare logic from __split_vma() in the same place where THP splitting also happens. At that point, both the VMA and the rmap(s) are write-locked. An annoying detail is that we can now call into the helper hugetlb_unshare_pmds() from two different locking contexts: 1. from hugetlb_split(), holding: - mmap lock (exclusively) - VMA lock - file rmap lock (exclusively) 2. hugetlb_unshare_all_pmds(), which I think is designed to be able to call us with only the mmap lock held (in shared mode), but currently only runs while holding mmap lock (exclusively) and VMA lock Backporting note: This commit fixes a racy protection that was introduced in commit b30c14cd6102 ("hugetlb: unshare some PMDs when splitting VMAs"); that commit claimed to fix an issue introduced in 5.13, but it should actually also go all the way back. [[email protected]: v2]

Package Linux Kernel
Published 2025-06-28
Last modified 2025-12-18
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

5.5

out of 10
Medium
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected versions

Linux kernel versions 2.6.20 and later are affected. Fixed in 5.10.239, 5.15.186, 6.1.142, 6.6.95, 6.12.35, 6.15.4, 6.16 and their respective stable series.

Affected from
≥ 2.6.20
Fixed in
✓ 5.10.239 5.10.x ✓ 5.15.186 5.15.x ✓ 6.1.142 6.1.x ✓ 6.6.95 6.6.x ✓ 6.12.35 6.12.x ✓ 6.15.4 6.15.x ✓ 6.16

References

The following references provide additional information about CVE-2025-38084 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

7 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2025-38084?

    CVE-2025-38084 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 2.6.20 onward and has been patched in 5.10.239, 5.15.186, 6.1.142 and others. CVE-2025-38084 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-38084?

    CVE-2025-38084 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2025-38084?

    Yes — CVE-2025-38084 has been patched. Fixed versions include 5.10.239, 5.15.186, 6.1.142 and others. If you are running Linux kernel 2.6.20 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-38084 actively exploited?

    No — CVE-2025-38084 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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