CVE-2025-39904

System interruption via uninitialized kexec buffer field

Published Oct 1, 2025 · Updated May 11, 2026

Use of uninitialized data in Linux kernel 6.16 through 6.16.7 allows local users to interrupt arm64 systems through kexec file loading. The arm64 load_other_segments() path leaves kexec_buf partly uninitialized, then kexec_add_buffer() reads its garbage random Boolean and triggers an invalid load. Reachability requires local access to the arm64 kexec file-loading path; the published impact is limited to system availability.

CVSS severity5.5
Medium
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

Use of uninitialized data in Linux kernel 6.16 through 6.16.7 allows local users to interrupt arm64 systems through kexec file loading. The arm64 load_other_segments() path leaves kexec_buf partly uninitialized, then kexec_add_buffer() reads its garbage random Boolean and triggers an invalid load. Reachability requires local access to the arm64 kexec file-loading path; the published impact is limited to system availability.

The record

CVE
CVE-2025-39904
Published
Oct 1, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-908, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 1, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=6.16
  2. Affected versionversion=bf454ec31add6790f6cdc88328e38901fcbbade6 <04d3cd43700a2d0fe4bfb1012a8ec7f2e34a3507
  3. Affected versionversion=bf454ec31add6790f6cdc88328e38901fcbbade6 <340cc9a3bd30b25edaf6a9708d41b5f2c10a054a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.16; version=bf454ec31add6790f6cdc88328e38901fcbbade6 <04d3cd43700a2d0fe4bfb1012a8ec7f2e34a3507; version=bf454ec31add6790f6cdc88328e38901fcbbade6 <340cc9a3bd30b25edaf6a9708d41b5f2c10a054a

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5CISA-ADPCVSS:3.1/AV:L/AC:L/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

CWE-908Use of Uninitialized Resource
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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