CVE-2026-99999 — In the Linux kernel, the following vulnerability has been resolved:¶
Key facts
CVE-2026-99999 is a Critical (9.3) vulnerability: In the Linux kernel, the following vulnerability has been resolved:. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-99999 |
| Severity | Critical (9.3) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-99999/ |
Details¶
English | 한국어
Description¶
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.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-99999 |
| CVSS Score | 9.3 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-99999/poc.py
Usage¶
# Run PoC against target
python3 poc.py --target <TARGET_URL>
# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>
⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.
Test Lab¶
This repository includes a Docker-based test environment with both vulnerable and patched applications.
Quick Start¶
# Clone and navigate to CVE directory
cd CVE-2026-99999
# Start both applications
docker-compose up -d
# Run tests
./run-tests.sh # Linux/Mac
./run-tests.ps1 # Windows PowerShell
Application Endpoints¶
| Application | URL | Status |
|---|---|---|
| Vulnerable App | http://localhost:8080 | Shows vulnerability |
| Patched App | http://localhost:8081 | Demonstrates fix |
Directory Structure¶
├── README.md # English documentation
├── README_KO.md # Korean documentation
├── poc.py # PoC detection script
├── docker-compose.yml # Container orchestration
├── run-tests.sh # Linux/Mac test runner
├── run-tests.ps1 # Windows test runner
├── vulnerable-app/ # Vulnerable version
│ ├── app.py
│ ├── Dockerfile
│ └── requirements.txt
└── patched-app/ # Fixed version
├── app.py
├── Dockerfile
└── requirements.txt
References¶
- https://git.kernel.org/stable/c/0fab003ef4698e0628060a45a48f14b43ba2a40a
- https://git.kernel.org/stable/c/32a8b0adaa18e52aaa0b246b5ffe683075354dbb
- https://git.kernel.org/stable/c/6785011f8b16abf40b1e9d8b2e332232b3e68822
- https://git.kernel.org/stable/c/94524b7b32691de2e2ce162c04d6cbc9106e5cbf
- https://git.kernel.org/stable/c/a464d950f31c89565cbaae038cc60db04fe01956
- https://git.kernel.org/stable/c/a65f69e0f38ffbed1b128029e09097436416dc8b
- https://git.kernel.org/stable/c/c3e33464746166264334641dc850a36eef7e6326
- https://git.kernel.org/stable/c/f3e835af6226f1dd12160cbd696081e9b6155de0
- https://pwn.ai/blog/Pwnescape
- https://vercel.com/blog/findings-from-the-1-million-dollar-vercel-sandbox-challenge
Generated by PoC Generator on 2026-10-16T07:36:06.436125072
Frequently asked questions¶
What is CVE-2026-99999?¶
CVE-2026-99999 is a Critical (9.3) vulnerability: In the Linux kernel, the following vulnerability has been resolved:. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-99999?¶
Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.
How do I block or mitigate CVE-2026-99999?¶
Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.
For authorized security testing and research only. See the full source and NVD record.