CVE-2026-35600 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in code.vikunja.io/api. O3 Security confirms whether CVE-2026-35600 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Vikunja has HTML Injection via Task Titles in Overdue Email Notifications
Real-World Exposure
code.vikunja.io/apiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, task titles are embedded directly into Markdown link syntax in overdue email notifications without escaping Markdown special characters. When rendered by goldmark and sanitized by bluemonday (which allows <a> and <img> tags), injected Markdown constructs produce phishing links and tracking pixels in legitimate notification emails. This vulnerability is fixed in 2.3.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | code.vikunja.io/api | all versions | 2.3.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for code.vikunja.io/api. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update code.vikunja.io/api to 2.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-35600 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-35600 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-35600. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-35600 in your dependencies?
O3 detects CVE-2026-35600 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.