---
title: "CVE-2026-99999: Linux Kernel - Denial of Service"
description: "Linux kernel contains a denial of service caused by improper validation of checksum_start in the ipv4 stack, letting attackers cause network header corruption, exploit requires sending malformed packets."
url: https://panop.io/threat-heartbeat/CVE-2026-99999/
---

# CVE-2026-99999 Linux Kernel - Denial of Service

Linux kernel contains a denial of service caused by improper validation of checksum\_start in the ipv4 stack, letting attackers cause network header corruption, exploit requires sending malformed packets.

CVSS base score 9.3 /10

Critical

CISA KEV

Not listed

Public exploit

Proof of concept available

Authentication

Not required

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-99999)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

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

Published

15 October 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version with the checksum validation fix.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-99999](https://nvd.nist.gov/vuln/detail/CVE-2026-99999)
- [https://git.kernel.org/stable/c/0fab003ef4698e0628060a45a48f14b43ba2a40a](https://git.kernel.org/stable/c/0fab003ef4698e0628060a45a48f14b43ba2a40a)
- [https://git.kernel.org/stable/c/32a8b0adaa18e52aaa0b246b5ffe683075354dbb](https://git.kernel.org/stable/c/32a8b0adaa18e52aaa0b246b5ffe683075354dbb)
- [https://git.kernel.org/stable/c/a464d950f31c89565cbaae038cc60db04fe01956](https://git.kernel.org/stable/c/a464d950f31c89565cbaae038cc60db04fe01956)
- [https://git.kernel.org/stable/c/c3e33464746166264334641dc850a36eef7e6326](https://git.kernel.org/stable/c/c3e33464746166264334641dc850a36eef7e6326)
- [https://git.kernel.org/stable/c/f3e835af6226f1dd12160cbd696081e9b6155de0](https://git.kernel.org/stable/c/f3e835af6226f1dd12160cbd696081e9b6155de0)
- [https://pwn.ai/blog/Pwnescape](https://pwn.ai/blog/Pwnescape)
- [https://vercel.com/blog/findings-from-the-1-million-dollar-vercel-sandbox-challenge](https://vercel.com/blog/findings-from-the-1-million-dollar-vercel-sandbox-challenge)
- [https://git.kernel.org/stable/c/6785011f8b16abf40b1e9d8b2e332232b3e68822](https://git.kernel.org/stable/c/6785011f8b16abf40b1e9d8b2e332232b3e68822)
- [https://git.kernel.org/stable/c/94524b7b32691de2e2ce162c04d6cbc9106e5cbf](https://git.kernel.org/stable/c/94524b7b32691de2e2ce162c04d6cbc9106e5cbf)
- [https://git.kernel.org/stable/c/a65f69e0f38ffbed1b128029e09097436416dc8b](https://git.kernel.org/stable/c/a65f69e0f38ffbed1b128029e09097436416dc8b)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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