CVE-2025-68796

Local kernel crash via zero-sized extent caching

Published Jan 13, 2026 · Updated Jan 13, 2026

Improper extent handling in Linux Kernel allows local users to crash the kernel through an F2FS zero-range operation. On an error path, f2fs_zero_range passes a zero length to f2fs_update_read_extent_cache_range, which inserts an invalid zero-sized extent before __update_extent_tree_range reaches a BUG check. Exploitation requires local access to invoke fallocate on an F2FS file, and the resulting kernel BUG interrupts the entire host rather than exposing 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

Improper extent handling in Linux Kernel allows local users to crash the kernel through an F2FS zero-range operation. On an error path, f2fs_zero_range passes a zero length to f2fs_update_read_extent_cache_range, which inserts an invalid zero-sized extent before __update_extent_tree_range reaches a BUG check. Exploitation requires local access to invoke fallocate on an F2FS file, and the resulting kernel BUG interrupts the entire host rather than exposing or modifying data.

The record

CVE
CVE-2025-68796
Published
Jan 13, 2026
Updated
Jan 13, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 13, 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=4.7
  2. Affected versionversion=6e9619499f53b22ead972e476c0e8341c997d929 <4f244c64efe628d277b916f47071adf480eb8646
  3. Affected versionversion=6e9619499f53b22ead972e476c0e8341c997d929 <7c37c79510329cd951a4dedf3f7bf7e2b18dccec
  4. Affected versionversion=6e9619499f53b22ead972e476c0e8341c997d929 <bac23833220a1f8fe8dfab7e16efa20ff64d7589
  5. Affected versionversion=6e9619499f53b22ead972e476c0e8341c997d929 <e50b81c50fcbe63f50405bb40f262162ff32af88
  6. Affected versionversion=6e9619499f53b22ead972e476c0e8341c997d929 <efe3371001f50a2d6f746b50bdc6f9f26b2089ec

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4.7; version=6e9619499f53b22ead972e476c0e8341c997d929 <4f244c64efe628d277b916f47071adf480eb8646; version=6e9619499f53b22ead972e476c0e8341c997d929 <7c37c79510329cd951a4dedf3f7bf7e2b18dccec; version=6e9619499f53b22ead972e476c0e8341c997d929 <bac23833220a1f8fe8dfab7e16efa20ff64d7589; version=6e9619499f53b22ead972e476c0e8341c997d929 <e50b81c50fcbe63f50405bb40f262162ff32af88; version=6e9619499f53b22ead972e476c0e8341c997d929 <efe3371001f50a2d6f746b50bdc6f9f26b2089ec

Published CVSS scores

5.5Amazon LinuxCVSS: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

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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