CVE-2023-34089
HIGHCVE-2023-34089 is a high-severity (CVSS 8.1) Cross-site Scripting (XSS) vulnerability in decidim. O3 Security confirms whether CVE-2023-34089 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Decidim Cross-site Scripting vulnerability in the processes filter
Blast Radius
decidim💎decidim💎decidim-core💎decidim-coreReal-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 participatory democracy framework, written in Ruby on Rails, originally developed for the Barcelona City government online and offline participation website. The processes filter feature is susceptible to Cross-site scripting. This allows a remote attacker to execute JavaScript code in the context of a currently logged-in user. An attacker could use this vulnerability to make other users endorse or support proposals they have no intention of supporting or endorsing. The problem was patched in version 0.27.3 and 0.26.7.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | decidim | ≥ 0.14.0&&< 0.26.7 | 0.26.7 |
| 💎RubyGems | decidim | ≥ 0.27.0&&< 0.27.3 | 0.27.3 |
| 💎RubyGems | decidim-core | ≥ 0.14.0&&< 0.26.7 | 0.26.7 |
| 💎RubyGems | decidim-core | ≥ 0.27.0&&< 0.27.3 | 0.27.3 |
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 0.26.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-34089 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-2023-34089 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-2023-34089. 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-2023-34089 in your dependencies?
O3 detects CVE-2023-34089 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.