CVE-2025-21667

System hang via truncated iomap scan offset

Published Jan 31, 2025 · Updated May 23, 2026

Infinite loop in Linux kernel 6.2 and affected stable branches allows local users to hang a 32-bit system by writing to XFS. In fs/iomap/buffered-io.c, iomap_write_delalloc_scan() derives a byte position from folio_next_index(), truncating the 64-bit file offset on 32-bit kernels. The path requires a local user writing to an XFS filesystem, and the resulting nonadvancing scan can consume CPU and hang the system.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in Linux kernel 6.2 and affected stable branches allows local users to hang a 32-bit system by writing to XFS. In fs/iomap/buffered-io.c, iomap_write_delalloc_scan() derives a byte position from folio_next_index(), truncating the 64-bit file offset on 32-bit kernels. The path requires a local user writing to an XFS filesystem, and the resulting nonadvancing scan can consume CPU and hang the system.

The record

CVE
CVE-2025-21667
Published
Jan 31, 2025
Updated
May 23, 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 23, 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=38be53c3fd7f4f4bd5de319a323d72f9f6beb16d <7ca4bd6b754913910151acce00be093f03642725
  2. Affected versionversion=6.1.92 <6.1.127
  3. Affected versionversion=6.2
  4. Affected versionversion=f43dc4dc3eff028b5ddddd99f3a66c5a6bdd4e78 <402ce16421477e27f30b57d6d1a6dc248fa3a4e4
  5. Affected versionversion=f43dc4dc3eff028b5ddddd99f3a66c5a6bdd4e78 <91371922704c8d82049ef7c2ad974d0a2cd1174d
  6. Affected versionversion=f43dc4dc3eff028b5ddddd99f3a66c5a6bdd4e78 <c13094b894de289514d84b8db56d1f2931a0bade

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=38be53c3fd7f4f4bd5de319a323d72f9f6beb16d <7ca4bd6b754913910151acce00be093f03642725; version=6.1.92 <6.1.127; version=6.2; version=f43dc4dc3eff028b5ddddd99f3a66c5a6bdd4e78 <402ce16421477e27f30b57d6d1a6dc248fa3a4e4; version=f43dc4dc3eff028b5ddddd99f3a66c5a6bdd4e78 <91371922704c8d82049ef7c2ad974d0a2cd1174d; version=f43dc4dc3eff028b5ddddd99f3a66c5a6bdd4e78 <c13094b894de289514d84b8db56d1f2931a0bade

Published CVSS scores

5.5NIST NVDCVSS: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.

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

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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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