vikunja: Improper Control of Generation of Code
CVE-2026-33336 is a high-severity improper control of generation of code vulnerability in vikunja from Go-vikunja, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected vikunja versions: >= 0.21.0, < 2.2.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.18% chance of exploitation within 30 days, higher than 68% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of vikunja you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Go-vikunja | vikunja | >= 0.21.0, < 2.2.0 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.5 | Medium | CNA (github.com) |
| CVSS 3.1 | 8.8 | High | NVD |
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).
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Control of Generation of Code
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
How developers prevent this class of flaw
- Refactor your program so that you do not have to dynamically generate code.
- Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
- Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
More Improper Control of Generation of Code vulnerabilities (CWE-94)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- vikunja.io/changelog/vikunja-v2.2.0-was-releasedRelease Notes
Other vulnerabilities in vikunja
- 8.8 High severity
- 7.1 High severity
- 7.1 High severity
Recent Improper Control of Generation of Code vulnerabilities
- 10.0 Critical severity
- 9.3 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.3 High severity
- 9.8 Critical severity
Spotted an error? Tell us.