CVE-2025-38085

Cross-process page-table access via unshare race

Published Jun 28, 2025 · Updated Aug 5, 2026

Race condition in Linux kernel hugetlb code allows local users to make GUP-fast walk another process's page tables during huge-page unsharing. huge_pmd_unshare() can drop the final reference to a shared page table while gup_fast() is concurrently traversing it, allowing that memory to become another process's active page table. Triggering requires low-privileged local access and a concurrent race; upstream reports cross-process page-table traversal but no immediate kernel memory corruption.

CVSS severity7.8
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Linux kernel hugetlb code allows local users to make GUP-fast walk another process's page tables during huge-page unsharing. huge_pmd_unshare() can drop the final reference to a shared page table while gup_fast() is concurrently traversing it, allowing that memory to become another process's active page table. Triggering requires low-privileged local access and a concurrent race; upstream reports cross-process page-table traversal but no immediate kernel memory corruption.

The record

CVE
CVE-2025-38085
Published
Jun 28, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 28, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.20
  2. Affected versionversion=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <034a52b5ef57c9c8225d94e9067f3390bb33922f
  3. Affected versionversion=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <1013af4f585fccc4d3e5c5824d174de2257f7d6d
  4. Affected versionversion=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <952596b08c74e8fe9e2883d1dc8a8f54a37384ec
  5. Affected versionversion=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <a3d864c901a300c295692d129159fc3001a56185
  6. Affected versionversion=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <a6bfeb97941a9187833b526bc6cc4ff5706d0ce9
  7. Affected versionversion=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <b7754d3aa7bf9f62218d096c0c8f6c13698fac8b
  8. Affected versionversion=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <fe684290418ef9ef76630072086ee530b92f02b8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.20; version=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <034a52b5ef57c9c8225d94e9067f3390bb33922f; version=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <1013af4f585fccc4d3e5c5824d174de2257f7d6d; version=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <952596b08c74e8fe9e2883d1dc8a8f54a37384ec; version=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <a3d864c901a300c295692d129159fc3001a56185; version=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <a6bfeb97941a9187833b526bc6cc4ff5706d0ce9; version=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <b7754d3aa7bf9f62218d096c0c8f6c13698fac8b; version=39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa <fe684290418ef9ef76630072086ee530b92f02b8

Published CVSS scores

7.8LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.7UbuntuCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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