CVE-2025-39901

Local kernel-memory disclosure via debugfs length misuse

Published Oct 1, 2025 · Updated Aug 19, 2026

Out-of-bounds read in the i40e driver in affected Linux kernels allows local users to read kernel memory through a debugfs file. The netdev_ops read handler passes snprintf's would-have-written length to copy_to_user after truncation, causing the copy to extend beyond its kzalloc buffer. Access requires the i40e interface and readable debugfs entries; debugfs is root-only by default, and a successful over-read exposes kernel memory or crashes the host.

CVSS severity7.1
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in the i40e driver in affected Linux kernels allows local users to read kernel memory through a debugfs file. The netdev_ops read handler passes snprintf's would-have-written length to copy_to_user after truncation, causing the copy to extend beyond its kzalloc buffer. Access requires the i40e interface and readable debugfs entries; debugfs is root-only by default, and a successful over-read exposes kernel memory or crashes the host.

The record

CVE
CVE-2025-39901
Published
Oct 1, 2025
Updated
Aug 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-125, T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 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=02e9c290814cc143ceccecb14eac3e7a05da745e <6fd8b30a5cb84d74015bc651799d1ab1e047946c
  2. Affected versionversion=02e9c290814cc143ceccecb14eac3e7a05da745e <70d3dad7d5ad077965d7a63eed1942b7ba49bfb4
  3. Affected versionversion=02e9c290814cc143ceccecb14eac3e7a05da745e <7d190963b80f4cd99d7008615600aa7cc993c6ba
  4. Affected versionversion=02e9c290814cc143ceccecb14eac3e7a05da745e <9fcdb1c3c4ba134434694c001dbff343f1ffa319
  5. Affected versionversion=02e9c290814cc143ceccecb14eac3e7a05da745e <ef40d9411469306e524e7887c51b709377e6ef65
  6. Affected versionversion=3.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=02e9c290814cc143ceccecb14eac3e7a05da745e <6fd8b30a5cb84d74015bc651799d1ab1e047946c; version=02e9c290814cc143ceccecb14eac3e7a05da745e <70d3dad7d5ad077965d7a63eed1942b7ba49bfb4; version=02e9c290814cc143ceccecb14eac3e7a05da745e <7d190963b80f4cd99d7008615600aa7cc993c6ba; version=02e9c290814cc143ceccecb14eac3e7a05da745e <9fcdb1c3c4ba134434694c001dbff343f1ffa319; version=02e9c290814cc143ceccecb14eac3e7a05da745e <ef40d9411469306e524e7887c51b709377e6ef65; version=3.12

Published CVSS scores

7.1CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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-125Out-of-bounds Read
T1005Data from Local System

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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