Dangerous "Theia IDE Docker" browser application.

[JacekHoleczek]

Discussion

I am using a (multiuser) Ubuntu 22.04 / x86_64 machine.

While playing with the official "Theia IDE Docker" browser application, I noticed that it is very dangerous.

I pulled the newest (as of 2026.01.24) official image using:

[...]$ apptainer pull ghcr.io/eclipse-theia/theia-ide/theia-ide:1.67.100

Then I can run it using:

[...]$ apptainer run /.../theia-ide_1.67.100.sif

or by simply executing:

[...]$ /.../theia-ide_1.67.100.sif

I noticed the following problems.

1. There is no built-in "password-based" nor "token-based" authentication. Anyone who connects to the exposed port will immediately get full access to my account (as I started the container).

Maybe you could add some reasonable authentication mechanism (effective by default at application startup)?

2. By default, the browser application starts as:

2026-01-24T...Z root INFO Theia app listening on http://0.0.0.0:3000.

It means it is open to the whole world (now see point 1. above again).
That is extremely dangerous, especially if I were using Docker. See the "My code-server got hacked; I have no idea how" discussion for the "code-server".

I noticed that it is sufficient to add the "--port" option when starting the container, and then it automatically switches to "localhost", e.g., when using:

[...]$ /.../theia-ide_1.67.100.sif -p

I get:

2026-01-24T...Z root INFO Theia app listening on http://127.0.0.1:3000.

Of course, the same happens when I explicitly use the "--hostname" option, too.

Maybe you could make the "localhost" the default setting?

3. At startup, it creates three subdirectories in "/tmp" (owned by "me"):

drwxr-xr-x me:me ... /tmp/theia_upload
drwxr-xr-x me:me ... /tmp/github-remote
drwxr-xr-x me:me ... /tmp/http-remote

It means that other users will not be able to run their own browser applications (on the same machine).

Maybe you could create all subdirectories with the "$(id --user)" appended to their names?

For example, I noticed that, when I connect to the browser application using Firefox, and then quit Firefox, it creates a "user-specific" subdirectory:

drwxr-xr-x me:me ... /tmp/vscode-typescript$(id --user)

[github-actions[bot]]

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[msujew]

Hey @JacekHoleczek, thanks for raising this discussion :)

I noticed that it is very dangerous.

Well, that's a relative term. In the end, the Theia IDE is a fully fledged code editor, with access to system resources (terminals, etc.) that "normal" web apps do not have. Anyone who runs the editor should be aware that anyone who can access the UI is able to essentially take over the whole underlying machine/container.

There is no built-in "password-based" nor "token-based" authentication.

That's a good point. AFAIK there is no open issue for this currently, so please go ahead and file a feature request for this. There has been little need in the past for this, see below.

It means that other users will not be able to run their own browser applications (on the same machine).

Yes, this is intentional. Theia is a single-tenant application, meaning that one server instance is for one user exclusively; This is entirely by design. You will find some discussions in GitHub, or I can just leave this here. VS Code and forks (Coder for example) follow the same design.

Historically, the Theia browser version has been used by companies that run Theia servers on Kubernetes (or similar orchestrator software) clusters, where they can easily spin up/down a new pod for a user on demand. The team has been working on theia cloud which does this as well. Usually, you would also put another layer of authentication on top of that to ensure that only the "correct" user has access to their workspace/server instance. This has historically alleviated the need for token based authentication within Theia.

[JacekHoleczek]

I now understand that the "Theia IDE Docker" browser application is unfortunately not suited for traditional/classical multi-user Linux servers.

It seems there exist (at least) two "VS Code" based tools that allow access through a modern web browser (with less functionality than Theia): "code-server" and "openvscode-server".

[rsoika]

I can't see the problem here. A docker container is at first an isolated application environment. It is not dangerous. The argument about the authentication is not a problem of theia. If you run for example an apache web server you could argue the same way.
It is the responsibility of the docker host environment to care about this issues. Typical you place a reverse proxy in front of your web containers to provide authentication layer.
So I think that the theia docker image is a good option for an isolated web ide.