CVE-2025-40279

Kernel-memory disclosure via uninitialized tc_ife padding

Published Dec 6, 2025 · Updated May 11, 2026

Information disclosure in the Linux kernel allows local users to read kernel memory through a crafted traffic-control netlink request. In tcf_connmark_dump(), a designated initializer leaves padding in the tc_ife opt structure uncleared, and nla_put() copies the entire structure into a userspace netlink message. The caller needs local low-privileged access and a reachable connmark traffic-control dump path; the disclosed bytes can expose residual kernel data, with no reported write or code-execution capability.

CVSS severity6.1
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

Information disclosure in the Linux kernel allows local users to read kernel memory through a crafted traffic-control netlink request. In tcf_connmark_dump(), a designated initializer leaves padding in the tc_ife opt structure uncleared, and nla_put() copies the entire structure into a userspace netlink message. The caller needs local low-privileged access and a reachable connmark traffic-control dump path; the disclosed bytes can expose residual kernel data, with no reported write or code-execution capability.

The record

CVE
CVE-2025-40279
Published
Dec 6, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 6, 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=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <218b67c8c8246d47a2a7910eae80abe4861fe2b7
  2. Affected versionversion=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <25837889ec062f2b7618142cd80253dff3da5343
  3. Affected versionversion=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <31e4aa93e2e5b5647fc235b0f6ee329646878f9e
  4. Affected versionversion=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <51cb05d4fd632596816ba44e882e84db9fb28a7e
  5. Affected versionversion=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <62b656e43eaeae445a39cd8021a4f47065af4389
  6. Affected versionversion=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <73cc56c608c209d3d666cc571293b090a471da70
  7. Affected versionversion=4.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <218b67c8c8246d47a2a7910eae80abe4861fe2b7; version=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <25837889ec062f2b7618142cd80253dff3da5343; version=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <31e4aa93e2e5b5647fc235b0f6ee329646878f9e; version=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <51cb05d4fd632596816ba44e882e84db9fb28a7e; version=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <62b656e43eaeae445a39cd8021a4f47065af4389; version=22a5dc0e5e3e8fef804230cd73ed7b0afd4c7bae <73cc56c608c209d3d666cc571293b090a471da70; version=4.0

Published CVSS scores

3.3Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
6.1OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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

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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