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VulnerabilityPublished Updated

CVE-2026-43040: Linux kernel · net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in ef3645606e4a635d5062a492f22b7f490852ee67 : update Linux kernel when convenient.

Data as of 6 Nov 2026, 16:21 UTC

Severity
Low

Rated Low by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch
Available – fixed in ef3645606e4a635d5062a492f22b7f490852ee67, b485eef3d97b7aae55ce669b6de555ec81f3d21c, ae05340ccaa9d347fe85415609e075545bec589f +5

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 31910575a9de61e78065e93846e8e7a4894a18bf, < ef3645606e4a635d5062a492f22b7f490852ee67
Fixed in
  • ef3645606e4a635d5062a492f22b7f490852ee67
LinuxLinuxAffected
  • ≥ 31910575a9de61e78065e93846e8e7a4894a18bf, < b485eef3d97b7aae55ce669b6de555ec81f3d21c
Fixed in
  • b485eef3d97b7aae55ce669b6de555ec81f3d21c
LinuxLinuxAffected
  • ≥ 31910575a9de61e78065e93846e8e7a4894a18bf, < ae05340ccaa9d347fe85415609e075545bec589f
Fixed in
  • ae05340ccaa9d347fe85415609e075545bec589f
LinuxLinuxAffected
  • ≥ 31910575a9de61e78065e93846e8e7a4894a18bf, < 11d7fe97421cfc81549940c20ed5ac9472d6db05
Fixed in
  • 11d7fe97421cfc81549940c20ed5ac9472d6db05
LinuxLinuxAffected
  • ≥ 31910575a9de61e78065e93846e8e7a4894a18bf, < 7f56d87e527bb5a13c3e8b0d5840cb6332822f6d
Fixed in
  • 7f56d87e527bb5a13c3e8b0d5840cb6332822f6d
LinuxLinuxAffected
  • ≥ 31910575a9de61e78065e93846e8e7a4894a18bf, < 4f810c686fde509d1cdaa706322d9d2531f8f1a4
Fixed in
  • 4f810c686fde509d1cdaa706322d9d2531f8f1a4

AI-suggested

A fix has been implemented and is available in the Linux kernel versions identified by the provided commit hashes. Users and administrators should update their Linux kernel to a fixed version to remediate this issue. No additional mitigation steps are required beyond applying the official patch.

Description

A vulnerability in the Linux kernel's IPv6 Neighbor Discovery (ndisc) component was fixed by initializing padding fields in the nduseroptmsg structure to zero. These padding fields were previously uninitialized, potentially leaking kernel memory data when processing Router Advertisements with user options.

References

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