CVE-2026-43040

Kernel-memory disclosure via uninitialized netlink padding

Published May 1, 2026 · Updated May 1, 2026

Information disclosure in Linux kernel releases containing the affected IPv6 code allows local users to read kernel data via netlink. The ndisc_ra_useropt function builds an RTM_NEWNDUSEROPT message without initializing the nduseropt_pad1, nduseropt_pad2, and nduseropt_pad3 fields, so residual kernel memory enters the message. Exposure requires a local low-privileged user to receive the notification after the host processes an IPv6 Router Advertisement containing user options; no data modification or code execution is reported.

CVSS severity7.1
High
EPSS probability0.12%
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 Linux kernel releases containing the affected IPv6 code allows local users to read kernel data via netlink. The ndisc_ra_useropt function builds an RTM_NEWNDUSEROPT message without initializing the nduseropt_pad1, nduseropt_pad2, and nduseropt_pad3 fields, so residual kernel memory enters the message. Exposure requires a local low-privileged user to receive the notification after the host processes an IPv6 Router Advertisement containing user options; no data modification or code execution is reported.

The record

CVE
CVE-2026-43040
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-909
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 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=2.6.24
  2. Affected versionversion=31910575a9de61e78065e93846e8e7a4894a18bf <11d7fe97421cfc81549940c20ed5ac9472d6db05
  3. Affected versionversion=31910575a9de61e78065e93846e8e7a4894a18bf <1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c
  4. Affected versionversion=31910575a9de61e78065e93846e8e7a4894a18bf <2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648
  5. Affected versionversion=31910575a9de61e78065e93846e8e7a4894a18bf <4f810c686fde509d1cdaa706322d9d2531f8f1a4
  6. Affected versionversion=31910575a9de61e78065e93846e8e7a4894a18bf <7f56d87e527bb5a13c3e8b0d5840cb6332822f6d
  7. Affected versionversion=31910575a9de61e78065e93846e8e7a4894a18bf <ae05340ccaa9d347fe85415609e075545bec589f
  8. Affected versionversion=31910575a9de61e78065e93846e8e7a4894a18bf <b485eef3d97b7aae55ce669b6de555ec81f3d21c
  9. Affected versionversion=31910575a9de61e78065e93846e8e7a4894a18bf <ef3645606e4a635d5062a492f22b7f490852ee67

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.24; version=31910575a9de61e78065e93846e8e7a4894a18bf <11d7fe97421cfc81549940c20ed5ac9472d6db05; version=31910575a9de61e78065e93846e8e7a4894a18bf <1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c; version=31910575a9de61e78065e93846e8e7a4894a18bf <2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648; version=31910575a9de61e78065e93846e8e7a4894a18bf <4f810c686fde509d1cdaa706322d9d2531f8f1a4; version=31910575a9de61e78065e93846e8e7a4894a18bf <7f56d87e527bb5a13c3e8b0d5840cb6332822f6d; version=31910575a9de61e78065e93846e8e7a4894a18bf <ae05340ccaa9d347fe85415609e075545bec589f; version=31910575a9de61e78065e93846e8e7a4894a18bf <b485eef3d97b7aae55ce669b6de555ec81f3d21c; version=31910575a9de61e78065e93846e8e7a4894a18bf <ef3645606e4a635d5062a492f22b7f490852ee67

Published CVSS scores

7.1NIST National Vulnerability DatabaseCVSS: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-909Missing Initialization of Resource

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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