CVE-2024-39910 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in decidim. O3 Security confirms whether CVE-2024-39910 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Cross-site scripting (XSS) in the decidim admin panel with QuillJS WYSWYG editor
Real-World Exposure
decidimReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
decidim is a Free Open-Source participatory democracy, citizen participation and open government for cities and organizations. The WYSWYG editor QuillJS is subject to potential XSS attach in case the attacker manages to modify the HTML before being uploaded to the server. The attacker is able to change e.g. to <svg onload=alert('XSS')> if they know how to craft these requests themselves. This issue has been addressed in release version 0.27.7. All users are advised to upgrade. Users unable to upgrade should review the user accounts that have access to the admin panel (i.e. general Administrators, and participatory space's Administrators) and remove access to them if they don't need it. Disable the "Enable rich text editor for participants" setting in the admin dashboard
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | decidim | all versions | 0.27.7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for decidim. 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 decidim to 0.27.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-39910 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-2024-39910 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-2024-39910. 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-2024-39910 in your dependencies?
O3 detects CVE-2024-39910 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.