[Bug]: VBoxSVC crashes (and takes out all running VMs) when attempting to make a new VM with an ISO generated by Cubic

[ArrayBolt3]

Version

7.2.10

Host OS Type

Linux

Host OS name + version

Kubuntu 26.04 LTS

Host Architecture

x86

Guest OS Type

Linux

Guest Architecture

x86

Guest OS name + version

Kubuntu 26.04 LTS

Component

GUI

What happened?

When attempting to create a new VM with an ISO built by Cubic (Custom Ubuntu ISO Creator), VBoxSVC crashes and all running VMs are forcibly terminated. This occurs on both release and development builds of VirtualBox, and has been occurring for quite some time.

Logs from journalctl related to the crash:

vbox-crash-logs.txt

How can we reproduce this?

Steps to reproduce:

1. Install the latest test build of VirtualBox from https://www.virtualbox.org/wiki/Testbuilds.
2. Obtain an Ubuntu ISO built with Cubic. You can generate this yourself (steps are included below), or you can use the Kubuntu Focus OEM image which is a Kubuntu ISO rebuilt with Cubic to include Kubuntu Focus tools on it.
3. Open VirtualBox.
4. In the top bar, click "New".
5. Set the VM name to cubic-test.
6. Click the ISO Image drop-down, then click "Other".
7. Navigate to the location of the Cubic-built ISO, and double-click it.

Expected result: VirtualBox should show the ISO name in the "ISO Image" field, and should attempt (not necessarily succeed but at least attempt) to autodetect the OS within the ISO.

Actual result: VBoxSVC crashes. A "VirtualBox - Error" window appears stating "Failed to set the global VirtualBox extra data for key GUI/RecentFolderCD to value {/path/to/dir/containing/iso}." The "Details" drop-down reveals "Callee RC: NS_ERROR_ABORT (0x80004004). If any VMs were running, "critical error" popups will appear and the VMs will be forcibly terminated.

To generate an ISO that can be used to reproduce this:

1. Download the latest Kubuntu 24.04 LTS ISO from here.
2. Install Cubic from here.
3. Click the "Select a project directory" button next to the drop-down field on the first page, then create a new directory with your desired name, then click "Select".
4. Click "Next".
5. Click the button next to the "Filename" field, then navigate to and select the Kubuntu ISO downloaded earlier.
6. Click "Next".
7. Wait for the "Customize" page to appear.
8. Click "Next" again without making any changes to the ISO.
9. On the "Select packages to be automatically removed..." screen, click "Next".
10. On the "Make changes to advanced options..." screen, click "Next".
11. On the "Select the compression for the Linux file system" screen, click "Next".
12. Wait for the ISO build to finish.

The built ISO can be used in the above reproduction steps to crash VBoxSVC.

Did you upload all of your necessary log files, screenshots, etc.?

• Yes, I've uploaded all pertinent files to this issue.

[ArrayBolt3]

By the way, it would be useful to know what in particular is causing VBox to crash so that we (KFocus) can adjust our ISO to avoid that. That way we can enhance usability with older (possibly unsupported) VirtualBox versions and builds.