CVE-2025-40337Network attack vector

Network-data integrity bypass via ignored checksum errors

Published Dec 9, 2025 · Updated Aug 5, 2026

Checksum validation bypass in affected Linux kernel branches allows remote attackers to pass corrupt stmmac packets as valid. stmmac_rx marks packets CHECKSUM_UNNECESSARY when checksum offload is enabled and the EtherType is recognized, without honoring the hardware csum_none error status. The condition requires an stmmac interface using receive checksum offload, and accepted corrupt traffic can alter data processed by higher network layers.

CVSS severity8.2
High
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Checksum validation bypass in affected Linux kernel branches allows remote attackers to pass corrupt stmmac packets as valid. stmmac_rx marks packets CHECKSUM_UNNECESSARY when checksum offload is enabled and the EtherType is recognized, without honoring the hardware csum_none error status. The condition requires an stmmac interface using receive checksum offload, and accepted corrupt traffic can alter data processed by higher network layers.

The record

CVE
CVE-2025-40337
Published
Dec 9, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=3.2
  2. Affected versionversion=3c20f72f9108b2fcf30ec63d8a4203736c01ccd0 <1aa319e0f12d2d761a31556b82a5852c98eb0bea
  3. Affected versionversion=3c20f72f9108b2fcf30ec63d8a4203736c01ccd0 <63fbe0e6413279d5ea5842e2423e351ded547683
  4. Affected versionversion=3c20f72f9108b2fcf30ec63d8a4203736c01ccd0 <719fcdf29051f7471d5d433475af76219019d33d
  5. Affected versionversion=3c20f72f9108b2fcf30ec63d8a4203736c01ccd0 <ee0aace5f844ef59335148875d05bec8764e71e8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.2; version=3c20f72f9108b2fcf30ec63d8a4203736c01ccd0 <1aa319e0f12d2d761a31556b82a5852c98eb0bea; version=3c20f72f9108b2fcf30ec63d8a4203736c01ccd0 <63fbe0e6413279d5ea5842e2423e351ded547683; version=3c20f72f9108b2fcf30ec63d8a4203736c01ccd0 <719fcdf29051f7471d5d433475af76219019d33d; version=3c20f72f9108b2fcf30ec63d8a4203736c01ccd0 <ee0aace5f844ef59335148875d05bec8764e71e8

Published CVSS scores

8.2Linux kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1565.002Transmitted Data Manipulation

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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