---
id: CVE-2026-99999
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv4: validate checksum_start before completing checksum

  If a packet with bad checksum metadata gets into the ipv4 stack,
  skb_checksum_help can corrupt the network hea…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv4: validate checksum_start before completing checksum

  If a packet with bad checksum metadata gets into the ipv4 stack,
  skb_checksum_help can corrupt the network hea…
severity: critical
cvss: 9.3
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f43798c27684ab925adde7d8acc34c78c6e50df8 <
    a464d950f31c89565cbaae038cc60db04fe01956
  - >-
    Linux >= f43798c27684ab925adde7d8acc34c78c6e50df8 <
    0fab003ef4698e0628060a45a48f14b43ba2a40a
  - >-
    Linux >= f43798c27684ab925adde7d8acc34c78c6e50df8 <
    94524b7b32691de2e2ce162c04d6cbc9106e5cbf
  - >-
    Linux >= f43798c27684ab925adde7d8acc34c78c6e50df8 <
    a65f69e0f38ffbed1b128029e09097436416dc8b
  - >-
    Linux >= f43798c27684ab925adde7d8acc34c78c6e50df8 <
    32a8b0adaa18e52aaa0b246b5ffe683075354dbb
  - >-
    Linux >= f43798c27684ab925adde7d8acc34c78c6e50df8 <
    f3e835af6226f1dd12160cbd696081e9b6155de0
  - >-
    Linux >= f43798c27684ab925adde7d8acc34c78c6e50df8 <
    c3e33464746166264334641dc850a36eef7e6326
  - >-
    Linux >= f43798c27684ab925adde7d8acc34c78c6e50df8 <
    6785011f8b16abf40b1e9d8b2e332232b3e68822
  - Linux 2.6.27
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T13:17:14.137'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-99999'
references:
  - url: 'https://git.kernel.org/stable/c/0fab003ef4698e0628060a45a48f14b43ba2a40a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/32a8b0adaa18e52aaa0b246b5ffe683075354dbb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6785011f8b16abf40b1e9d8b2e332232b3e68822'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/94524b7b32691de2e2ce162c04d6cbc9106e5cbf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a464d950f31c89565cbaae038cc60db04fe01956'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a65f69e0f38ffbed1b128029e09097436416dc8b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c3e33464746166264334641dc850a36eef7e6326'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f3e835af6226f1dd12160cbd696081e9b6155de0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://pwn.ai/blog/Pwnescape'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://vercel.com/blog/findings-from-the-1-million-dollar-vercel-sandbox-challenge
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99999.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-99999'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2553429'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-99999'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-99999'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-99999.mbox
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ingestedAt: '2026-10-15T13:06:33.282Z'
cwe:
  - CWE-787
scores:
  nvd: 9.3
  vendor: 8.8
  cna: 9.3
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:49:03.519458Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

ipv4: validate checksum_start before completing checksum

If a packet with bad checksum metadata gets into the ipv4 stack,
skb_checksum_help can corrupt the network header and cause a bunch of
mischief.

This was discovered and reported by Paulos, and has been reporoduced
by others independently since.

We really shouldn't allow such packets in, but as a defence
in depth measure, let's also check before we complete the checksum.

A more complete validation at input is forthcoming, but needs more work.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Critical · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99999.json)