CVE-2025-21665

Local write hang via truncated file offset

Published Jan 31, 2025 · Updated May 11, 2026

Denial of service in the Linux kernel 5.12 and later allows local users to hang XFS writes through files larger than 4 GiB. folio_seek_hole_data() stores a 64-bit file offset in an unsigned long, truncating it on 32-bit builds so the seek loop cannot advance. Exploitation requires local XFS write access on a 32-bit kernel and interrupts the affected write path without reported disclosure or privilege gain.

CVSS severity5.5
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux kernel 5.12 and later allows local users to hang XFS writes through files larger than 4 GiB. folio_seek_hole_data() stores a 64-bit file offset in an unsigned long, truncating it on 32-bit builds so the seek loop cannot advance. Exploitation requires local XFS write access on a 32-bit kernel and interrupts the affected write path without reported disclosure or privilege gain.

The record

CVE
CVE-2025-21665
Published
Jan 31, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-835, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 31, 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=5.12
  2. Affected versionversion=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <09528bb1a4123e2a234eac2bc45a0e51e78dab43
  3. Affected versionversion=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <280f1fb89afc01e7376f59ae611d54ca69e9f967
  4. Affected versionversion=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <64e5fd96330df2ad278d1c4edcca581f26e5f76e
  5. Affected versionversion=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <80fc836f3ebe2f2d2d2c80c698b7667974285a04
  6. Affected versionversion=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <f505e6c91e7a22d10316665a86d79f84d9f0ba76

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <09528bb1a4123e2a234eac2bc45a0e51e78dab43; version=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <280f1fb89afc01e7376f59ae611d54ca69e9f967; version=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <64e5fd96330df2ad278d1c4edcca581f26e5f76e; version=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <80fc836f3ebe2f2d2d2c80c698b7667974285a04; version=54fa39ac2e00b1b8c2a7fe72e648773ffa48f76d <f505e6c91e7a22d10316665a86d79f84d9f0ba76

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Oracle LinuxCVSS: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-835Loop with Unreachable Exit Condition ('Infinite Loop')
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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