Showing the exploting Copy Fail CVE-2026-31431 in an Ubuntu 24.04 just launched in Google Cloud, and how to fix it

So I show here how I launched a fresh Ubuntu 24.04 in Google Cloud, on 2026-05-04, and demostrate the exploit of escalation privileges Copy Fail (CVE-2026-31431) which allows you to become root from a regular user account in almost any Linux since year 2017.

It consists in the execution of a Python 3 code, which is only 732 bytes.

I show how I fixed it by upgrading the kernel and rebooting.

Here you can see the original tweet I saw: https://x.com/DarkWebInformer/status/2049579219190165658?s=20

And access the code: https://github.com/theori-io/copy-fail-CVE-2026-31431

I also tried on a fresh deployed Ubuntu 26.04 LTS and it was not affected by the exploit.

Vibe coding with Google Antigravity, new features, to a project, in real time

This video shows real example of my workflow, in real time, on how I programmed with Google Antigravity some new features, like adding discount coupons, for my commercial web project for quickly audio conversion https://audioconverter.carlesmateo.com/

I show some problems when working with Gemini 3 Flash, and how I instructed the IA to fix them.

Resizing the disk of your Ubuntu Server in Google Cloud GCP without rebooting

If you are running your instances in Google Gloud Compute Engine and you want to increase the size of the Disk without having to reboot, this video explains step by step how you can do it.

Go to Disks in GCP, select the disk of the instance you want to increase, then press Edit.

After you increase the Disk in Google Cloud Dashboard, then ssh to you instance.

There type:

lsblk

in order to list the devices.

In my case is sda and I want to grow the partition 1.

So I proceed with:

sudo growpart /dev/sda 1

Which growing from 30GB to 40GB produces the output:

CHANGED: partition=1 start=2324480 old: size=60590047 end=62914526 new: size=81561567 end=83886046

Is you type lsblk again you’ll see the new size.

But if you type df -h you’ll see that Linux still doesn’t see the space.

To finalize and claim the additional space execute (in my case is sda1):

sudo resize2fs /dev/sda1

Sudo problems in Ubuntu 26.04 LTS with Google Cloud: I’m sorry user. I’m afraid I can’t do that

I show in the video, how briefly after using sudo, it stops working.

I did this proof of concept and, I got the same problem: 

sleep 300 && sudo cat /etc/lsb-release

Checking with: 

id -nG

clearly showed that my user is part of google-sudoers But then:

journalctl -u google-guest-agent -f

Displays:

Apr 26 17:54:07 ubuntu26-04 google_guest_agent[851]: Adding existing user carles_mateo to google-sudoers group.
Apr 26 17:54:07 ubuntu26-04 gpasswd[89648]: user carles_mateo added by root to group google-sudoers
Apr 26 17:54:07 ubuntu26-04 google_guest_agent[851]: Updating keys for user carles_mateo.
Apr 26 17:54:11 ubuntu26-04 google_guest_agent[851]: Updating keys for user carles_mateo.
Apr 26 17:57:11 ubuntu26-04 google_guest_agent[851]: ERROR non_windows_accounts.go:219 invalid ssh key entry - expired key: carles_mateo:...google-ssh {"userName":"carles.mateo@gmail.com","expireOn":"2026-04-26T17:57:05+0000"}
Apr 26 17:57:11 ubuntu26-04 google_guest_agent[851]: ERROR non_windows_accounts.go:219 invalid ssh key entry - expired key: carles_mateo:ssh-rsa...
Apr 26 17:57:11 ubuntu26-04 google_guest_agent[851]: Removing user carles_mateo.
Apr 26 17:57:11 ubuntu26-04 gpasswd[89736]: user carles_mateo removed by root from group google-sudoers

Installing Ubuntu 26.04 LTS in Google Cloud Compute Engine

The video shows step by step how to create an Instance in Google Cloud Compute Engine of the type e2, increase the size of the disk, and install Ubuntu 26.04 LTS Server.

Also shows how the new htop looks, with new IO options.

You know that utilites from coreutils have been rewriten in Rust, like sudo. I was wondering if it would work well. I thoguht I was encountering the first problems, after I experienced that when launched sudo, like in example, a sudo apt install package , sudo then stops working and I’ve to exit the shell and relogin.

I found that it is Google Cloud that removes my user from google-sudoers after 3 minutes.

I explain it in here.

Solving silent exit error on eZ Launchpad

You have installed eZ Launchpad, and you can execute the binary ez from your home folder or other paths, however when you execute it from a project folder you cloned with git (with its .platform.app.yaml file) ez returns to prompt without any error message.

The exit code is 255, but even if you strace the process you don’t find the exact problem.

Inside your project you run ez without any argument in a clean install of Ubuntu 24.04 LTS with PHP 8.3, or with PHP 8.4, without xDebug, without opcache, without memory limit… nothing works with no visible error message in the logs or in the error output. However if you run it outside the project folder, it works, and it displays the typical help messages.

I reproduced this behavior on several Ubuntu computers. The fix I found is to execute ez with PHP 8.1

You can install PHP8.1 from ondrej repository, then you can update alternates to execute PHP 8.1 by default in your system, or you create the project by invoking ez with PHP 8.1 explicitly with:

php8.1 ~/ez create

This will kickstart the creation of your ez project based on Docker containers.

Installing PHP environment for development in Windows

This article is for my students learning PHP, or for any student that wants to learn PHP and uses a Windows computer for that.

For this we will install:

XAMPP, which is available for Windows, Mac OS and Linux.

You can download it from: https://www.apachefriends.org/

XAMPP installs together:

  • Apache
  • MariaDB
  • PHP
  • Perl

Install WAMPP instead of XAMP (if you prefer WAMPP)

Alternatively you can install WAMPP, which installs:

  • Apache
  • MySQL
  • PHP
  • PHPMyAdmin

https://www.wampserver.com/en/

Development IDE

As Development Environment we will use PHPStorm, from Jetbrains.

https://www.jetbrains.com/phpstorm/

Testing the installation of XAMPP

The default directory for the PHP files is C:\xampp\htdocs

Create a file in c:\xampp\htdocs named hello.php

<?php
$s_today = date("Y-m-d");
echo "Hello! Today is ".$s_today;
?>

Now start Apache:

  1. Open the XAMPP Control Panel
  2. Start the Apache Server
You should see at least port 80 for Apache

And test the new page, with the browser, opening:

http://localhost/hello.php