[Bug]: VirtualBox 7.2.0: NAT networking breaks when adding additional port forwarding rule => fixed in next 7.2.x maintenance release

[dldydgns]

Version

7.2.0

Host OS Type

Windows

Host OS name + version

Windows 11 Build 26100.6584

Host Architecture

ARM

Guest OS Type

Linux

Guest Architecture

ARM

Guest OS name + version

ubuntu-24.04.2-live-server-amd64

Component

Network

What happened?

When configuring multiple port forwarding rules in VirtualBox 7.2.0, NAT networking breaks after adding an additional rule for Jenkins(8080).

Note:

VMs are installed in SMB Storage with another network:
My IP Address: 192.168.0.111
iptime router: 192.168.0.1
SMB storage server(TrueNAS): 192.168.0.52

Setup:

※ set ip address with new netplan yaml file

sudo ls /etc/netplan
sudo nano /etc/netplan/01-netcfg.yaml
sudo rm /etc/netplan/50-cloud-init.yaml 

Guest1 (OS: ubuntu): Set Static IP address → 10.0.2.15
Guest2 (OS: ubuntu): Set Static IP address → 10.0.2.20

Add NAT Network with default configuration and add:
Guest1 (ubuntu1): SSH forwarded from VirtualBox localhost:2015 → 10.0.2.15:22
Guest2 (ubuntu2): SSH forwarded from VirtualBox localhost:2020 → 10.0.2.20:22

[Check SSH port forwarding to both VMs works correctly.]

Added port-forwarding: TCP Host localhost:8080 → Guest 10.0.2.15:8080

Result:

SSH connections to both guests fail, Internet access from the guests also fails

VBox.log
VBoxHardening.log

⚠️ This problem only occurs on VirtualBox 7.0.x.
When testing on VirtualBox 7.1.10, the same configuration works without issues.y

How can we reproduce this?

How can we reproduce this?

Install VirtualBox 7.0.x on a Linux host (e.g., Ubuntu 24.04).

Create two Ubuntu 22.04 minimal guest VMs (ubuntu1 and ubuntu2).

Configure the following NAT port forwarding rules:

localhost:2015 → ubuntu1:22

localhost:2020 → ubuntu2:22

Verify that SSH works to both guests and that ubuntu1 ↔ ubuntu2 can ping each other.

Add a new NAT port forwarding rule:

localhost:8080 → ubuntu1:8080

Observe the result:

1. SSH fails from host to both VMs
2. Internet access from the guests fails

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

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

[AlexanderEichner]

Thanks for the report, this will be fixed in the next maintenance release.

[dldydgns]

Thank you for the quick solution.