CVE-2026-43040

CVEs › CVE-2026-43040

Description

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak When processing Router Advertisements with user options the kernel builds an RTM_NEWNDUSEROPT netlink message. The nduseroptmsg struct has three padding fields that are never zeroed and can leak kernel data The fix is simple, just zeroes the padding fields.

Overview

State: PUBLISHED
Assigner (CNA): Linux
CVSS severity: high
CVSS score: 7.1 / 10
CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Effective score: 7.1 / 10 HIGH source: CNA overview
CWE(s): —
Reserved: 2026-05-01
Published: 2026-05-01 16:15 UTC
Last updated: 2026-05-12 00:16 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/43xxx/CVE-2026-43040.json
Linked Threat: CVE-2026-43040 — CVE-2026-43040

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-05-01 15:16:50 UTC
NVD last modified: 2026-05-08 18:53:20 UTC
NVD CVSS v3.1: 7.1 / 10 HIGH source: nvd@nist.gov
NVD CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Exploitability subscore: 1.8 / 10
Impact subscore: 5.2 / 10
EPSS score: 0.0001 (probability of exploitation in next 30 days)
EPSS percentile: 2.55% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD-assigned CWE(s): CWE-909 (differs from the CNA list above)

NVD / KEV / EPSS data refreshed 2026-05-25 09:11 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-26639
Assigner: Linux
Published: May 1, 2026, 2:15:37 PM
Updated: May 11, 2026, 10:16:33 PM
EUVD base score: 0.0 / 10
EUVD-reported EPSS: 0.0100
Vendors: Linux
Products: Linux (patch: 6.19.12)

Linux (31910575a9de61e78065e93846e8e7a4894a18bf <ef3645606e4a635d5062a492f22b7f490852ee67)

Linux (patch: 6.18.22)

Linux (patch: 0)

Linux (31910575a9de61e78065e93846e8e7a4894a18bf <1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c)

Linux (31910575a9de61e78065e93846e8e7a4894a18bf <ae05340ccaa9d347fe85415609e075545bec589f)

Linux (31910575a9de61e78065e93846e8e7a4894a18bf <2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648)

Linux (patch: 7.0)

Linux (patch: 6.6.134)

Linux (31910575a9de61e78065e93846e8e7a4894a18bf <b485eef3d97b7aae55ce669b6de555ec81f3d21c)

Linux (patch: 5.15.203)

Linux (31910575a9de61e78065e93846e8e7a4894a18bf <11d7fe97421cfc81549940c20ed5ac9472d6db05)

Linux (patch: 5.10.253)

Linux (31910575a9de61e78065e93846e8e7a4894a18bf <4f810c686fde509d1cdaa706322d9d2531f8f1a4)

Linux (patch: 6.1.168)

Linux (patch: 6.12.81)

Linux (31910575a9de61e78065e93846e8e7a4894a18bf <7f56d87e527bb5a13c3e8b0d5840cb6332822f6d)

Linux (2.6.24)

ENISA description: In the Linux kernel, the following vulnerability has been resolved: net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak When processing Router Advertisements with user options the kernel builds an RTM_NEWNDUSEROPT netlink message. The nduseroptmsg struct has three padding fields that are never zeroed and can leak kernel data The fix is simple, just zeroes the padding fields.

EUVD references (8)

Affected products (2)

Vendor	Product	Versions	Platforms
Linux	Linux	`31910575a9de61e78065e93846e8e7a4894a18bf` (affected), `31910575a9de61e78065e93846e8e7a4894a18bf` (affected), `31910575a9de61e78065e93846e8e7a4894a18bf` (affected), `31910575a9de61e78065e93846e8e7a4894a18bf` (affected), `31910575a9de61e78065e93846e8e7a4894a18bf` (affected), `31910575a9de61e78065e93846e8e7a4894a18bf` (affected), `31910575a9de61e78065e93846e8e7a4894a18bf` (affected), `31910575a9de61e78065e93846e8e7a4894a18bf` (affected)	—
Linux	Linux	`2.6.24` (affected), `0` (unaffected), `5.10.253` (unaffected), `5.15.203` (unaffected), `6.1.168` (unaffected), `6.6.134` (unaffected), `6.12.81` (unaffected), `6.18.22` (unaffected), `6.19.12` (unaffected), `7.0` (unaffected)	—

Affected products — CPE 2.3 (7) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*

Vendor references (8)

References embedded in the original CVE record by the assigning CNA.

Web references (14)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

http://cwe.mitre.org/data/definitions/909.html rapid7:cwe.mitre.org
https://attackerkb.com/topics/CVE-2026-43040 rapid7:attackerkb.com
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-26639 rapid7:euvd.enisa.europa.eu
https://git.kernel.org/stable/c/11d7fe97421cfc81549940c20ed5ac9472d6db05 tenable:git.kernel.org
https://git.kernel.org/stable/c/1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c tenable:git.kernel.org
https://git.kernel.org/stable/c/2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648 tenable:git.kernel.org
https://git.kernel.org/stable/c/4f810c686fde509d1cdaa706322d9d2531f8f1a4 tenable:git.kernel.org
https://git.kernel.org/stable/c/7f56d87e527bb5a13c3e8b0d5840cb6332822f6d tenable:git.kernel.org
https://git.kernel.org/stable/c/ae05340ccaa9d347fe85415609e075545bec589f tenable:git.kernel.org
https://git.kernel.org/stable/c/b485eef3d97b7aae55ce669b6de555ec81f3d21c tenable:git.kernel.org
https://git.kernel.org/stable/c/ef3645606e4a635d5062a492f22b7f490852ee67 tenable:git.kernel.org
https://nvd.nist.gov/vuln/detail/CVE-2026-43040 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-43040 tenable:www.cve.org
https://www.first.org/epss/ tenable:www.first.org

NVD-tagged references (8)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://git.kernel.org/stable/c/11d7fe97421cfc81549940c20ed5ac9472d6db05 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch
https://git.kernel.org/stable/c/1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch
https://git.kernel.org/stable/c/2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch
https://git.kernel.org/stable/c/4f810c686fde509d1cdaa706322d9d2531f8f1a4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch
https://git.kernel.org/stable/c/7f56d87e527bb5a13c3e8b0d5840cb6332822f6d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch
https://git.kernel.org/stable/c/ae05340ccaa9d347fe85415609e075545bec589f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch
https://git.kernel.org/stable/c/b485eef3d97b7aae55ce669b6de555ec81f3d21c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch
https://git.kernel.org/stable/c/ef3645606e4a635d5062a492f22b7f490852ee67 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch

Remediations (17)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

Microsoft and Adobe Patch Tuesday, April 2026 Security Update Review

web:blog.qualys.com

With Qualys Policy Audit's out-of-the-box mitigation or Compensatory Controls, which reduce the risk of a vulnerability being exploited because the remediation ( fix / patch ) cannot be done immediately, these security controls are not recommended by any industry standards, such as CIS and DISA-STIG.

2026-05-23 20:23 UTC
CISA Warns of Exploited Microsoft Defender 0-Day Flaws

web:cyberpress.org

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added two actively exploited Microsoft Defender vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog, issuing an urgent remediation directive for federal agencies with a due date of June 3, 2026 .

2026-05-23 20:23 UTC
cPanel Vulnerability CVE-2026-41940 Puts 70 Million Websites at Risk ...

web:cyberunit.com

A critical cPanel and WHM authentication bypass ( CVE - 2026 -41940, CVSS 9.8) exposes roughly 1.5 million servers and an estimated 70 million websites. Attackers exploited the flaw for two months before the April 28, 2026 patch .

2026-05-23 20:23 UTC
Nvd - Cve-2026-43040

web:nvd.nist.gov

Official websites use .gov A .gov website belongs to an official government organization in the United States.

2026-05-23 20:23 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-05-23 20:23 UTC
April 2026 Patch Tuesday: Updates and Analysis | CrowdStrike

web:www.crowdstrike.com

Microsoft's April 2026 Patch Tuesday addresses 164 CVEs , featuring 8 Critical vulnerabilities, one exploited zero-day, and one disclosed zero-day.

2026-05-23 20:23 UTC
Docker Security Bypass (CVE-2026-34040): Critical Patch & Mitigation ...

web:www.cyera.com

Cyera Research identifies CVE - 2026 -34040, a critical Docker bypass. Learn how 1MB+ requests silence security plugins and how to patch Docker Engine 29.3.1 today.

2026-05-23 20:23 UTC
2 New Microsoft Defender Zero-Days Exploited—Patch Now ... - Forbes

web:www.forbes.com

Microsoft has confirmed an emergency security update as CISA warns that two new Defender zero-days are being exploited by attackers.

2026-05-23 20:23 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-05-23 20:23 UTC
Vulnerability Remediation vs. Mitigation: What are the Differences ...

web:www.secure.com

Learn the difference between vulnerability remediation and mitigation , and how a risk-based strategy can strengthen your security posture.

2026-05-23 20:23 UTC
Security Advisory Bulletin 064 | Ubiquiti Community

web:community.ui.com

Published: May 21, 2026 Updated: May 22, 2026 Version: 1.1 Revision: 1.1 Summary 1 of 5 A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS devices to execute a Command Injection. Affected Products: UniFi OS Server (Version 5.0.6 and earlier) Mitigation : Update your UniFi OS Server to Version 5.0.8 or later ...

2026-05-26 02:45 UTC
Security: CVE-2026-41940 - cPanel & WHM / WP2 Security Update 04/28 ...

web:support.cpanel.net

04/28/26 04:36PM CST: Updated article to include patched versions. 04/28/26 03:19PM CST: Updated article to reflect changes in mitigation steps 04/28/26 12:05PM CST: Initial article published. Situation An authentication bypass security issue has been identified in the cPanel software (including DNSOnly) affecting all versions after 11.40.

2026-05-26 02:45 UTC
Critical Patches Issued for Microsoft Products, April 14, 2026

web:www.cisecurity.org

<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...

2026-05-26 02:45 UTC
The Docker CVE-2026-34040 Nightmare | Hexon

web:www.hexon.bot

The body-truncation behavior has existed for approximately ten years. It was partially addressed in July 2024 ( CVE -2024-41110) but the fix was incomplete and did not handle oversized bodies. What is the relationship between CVE - 2026 -34040 and AI security? This vulnerability represents a new class of AI agent risk: autonomous security bypass.

2026-05-26 02:45 UTC
National Vulnerability Database | NIST

web:www.nist.gov

NIST maintains the National Vulnerability Database (NVD), a repository of information on software and hardware flaws that can compromise computer security. This is a key piece of the nation's cybersecurity infrastructure.

2026-05-26 02:45 UTC
CVE-2026-41940 Explained: The cPanel & WHM Authentication Bypass That ...

web:www.picussecurity.com

CVE - 2026 -41940 explained: how a CRLF injection bypassed cPanel & WHM authentication on 1.5M servers. Root cause, exploit chain, IOCs, and patch guidance.

2026-05-26 02:45 UTC
CVE-2026-41940: cPanel & WHM Authentication Bypass - Rapid7

web:www.rapid7.com

On April 28, 2026 , a critical vulnerability affecting cPanel & WHM and WP Squared was announced. CVE - 2026 -41940 is an authentication bypass bug with a CVSS score of 9.8, and exploitation in the wild has begun.

2026-05-26 02:45 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-43040.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ndisc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            },
            {
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          "vendor": "Linux",
          "versions": [
            {
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              "version": "2.6.24"
            },
            {
              "lessThan": "2.6.24",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.253",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.203",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.168",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.134",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.81",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.22",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "versionStartIncluding": "2.6.24",
                  "vulnerable": true
                },
                {
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                },
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                },
                {
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                },
                {
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "2.6.24",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak\n\nWhen processing Router Advertisements with user options the kernel\nbuilds an RTM_NEWNDUSEROPT netlink message. The nduseroptmsg struct\nhas three padding fields that are never zeroed and can leak kernel data\n\nThe fix is simple, just zeroes the padding fields."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T22:16:33.369Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c"
        },
        {
          "url": "https://git.kernel.org/stable/c/2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648"
        },
        {
          "url": "https://git.kernel.org/stable/c/11d7fe97421cfc81549940c20ed5ac9472d6db05"
        },
        {
          "url": "https://git.kernel.org/stable/c/7f56d87e527bb5a13c3e8b0d5840cb6332822f6d"
        },
        {
          "url": "https://git.kernel.org/stable/c/4f810c686fde509d1cdaa706322d9d2531f8f1a4"
        },
        {
          "url": "https://git.kernel.org/stable/c/b485eef3d97b7aae55ce669b6de555ec81f3d21c"
        },
        {
          "url": "https://git.kernel.org/stable/c/ef3645606e4a635d5062a492f22b7f490852ee67"
        },
        {
          "url": "https://git.kernel.org/stable/c/ae05340ccaa9d347fe85415609e075545bec589f"
        }
      ],
      "title": "net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43040",
    "datePublished": "2026-05-01T14:15:37.364Z",
    "dateReserved": "2026-05-01T14:12:55.978Z",
    "dateUpdated": "2026-05-11T22:16:33.369Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}