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Linux KernelOperating system · Linux

CVE-2026-43040

HIGH · 7.1 CVSS v3.1 Published 2026-05-01
Fix available
A fix is available. Upgrade to 5.10.253 / 5.15.203 or later.
See remediation →
73/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.24, < 5.10.253>= 5.11, < 5.15.203>= 5.16, < 6.1.168>= 6.2, < 6.6.134>= 6.7, < 6.12.81>= 6.13, < 6.18.22>= 6.19, < 6.19.12= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.10.253 / 5.15.203 / 6.1.168 or later
Fixed in 5.10.2535.15.2036.1.168
Vendor patch git.kernel.org →
Recommended fix High confidence

6.6.134 (or latest stable 6.6.x release; alternatively 6.1.168, 5.15.203, or 5.10.253 depending on your branch)

  1. Identify the currently running kernel version using `uname -r`
  2. Determine which version branch your current kernel belongs to based on the affected ranges provided
  3. Upgrade to a kernel version >= 5.10.253 if on the 5.10.x branch, >= 5.15.203 if on 5.11-5.15.x, >= 6.1.168 if on 5.16-6.1.x, or >= 6.6.134 if on 6.2-6.6.x
  4. On Debian/Ubuntu: Run `sudo apt update && sudo apt upgrade linux-image-generic`
  5. On RHEL/CentOS: Run `sudo yum update kernel`
  6. On Fedora: Run `sudo dnf update kernel`
  7. Reboot the system using `sudo reboot` to load the new kernel
  8. Verify the fix is applied by checking the kernel version with `uname -r` and confirming it matches a fixed release
Caveat Kernel upgrades may require rebooting production systems; ensure compatibility with custom modules or drivers before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-43040 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data