CVE-2025-39992

Kernel crash via unstable VMA tree dereference

Published Oct 15, 2025 · Updated Oct 15, 2025

NULL pointer dereference in the Linux kernel 6.8 allows local users to crash the kernel through a fork-and-swapoff race. During dup_mmap(), a fatal signal leaves XA_ZERO_ENTRY markers in a partially initialized VMA tree exposed on mmlist, and unuse_mm() treats a marker as a VMA and dereferences it. Reaching the swapoff path requires CAP_SYS_ADMIN; a successful race produces a kernel OOPS and interrupts the host rather than disclosing or modifying data.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux kernel 6.8 allows local users to crash the kernel through a fork-and-swapoff race. During dup_mmap(), a fatal signal leaves XA_ZERO_ENTRY markers in a partially initialized VMA tree exposed on mmlist, and unuse_mm() treats a marker as a VMA and dereferences it. Reaching the swapoff path requires CAP_SYS_ADMIN; a successful race produces a kernel OOPS and interrupts the host rather than disclosing or modifying data.

The record

CVE
CVE-2025-39992
Published
Oct 15, 2025
Updated
Oct 15, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 15, 2025Record 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=6.8
  2. Affected versionversion=d2406291483775ecddaee929231a39c70c08fda2 <1367da7eb875d01102d2ed18654b24d261ff5393
  3. Affected versionversion=d2406291483775ecddaee929231a39c70c08fda2 <4e5f060d7347466f77aaff1c0d5a6c4f1fb217ac
  4. Affected versionversion=d2406291483775ecddaee929231a39c70c08fda2 <9cddad3b26dac830407d2d3c0de5205ff6d6dda0
  5. Affected versionversion=d2406291483775ecddaee929231a39c70c08fda2 <e4e99d69b8b8295c501b2eef89e13306b738b667

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=6.8; version=d2406291483775ecddaee929231a39c70c08fda2 <1367da7eb875d01102d2ed18654b24d261ff5393; version=d2406291483775ecddaee929231a39c70c08fda2 <4e5f060d7347466f77aaff1c0d5a6c4f1fb217ac; version=d2406291483775ecddaee929231a39c70c08fda2 <9cddad3b26dac830407d2d3c0de5205ff6d6dda0; version=d2406291483775ecddaee929231a39c70c08fda2 <e4e99d69b8b8295c501b2eef89e13306b738b667

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.0Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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