CVE-2021-39133 is a medium-severity (CVSS 6.8) Cross-Site Request Forgery (CSRF) vulnerability in org.rundeck:rundeck-core. O3 Security confirms whether CVE-2021-39133 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Cross-Site Request Forgery (CSRF) can run untrusted code on Rundeck server
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2021-39133 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 365,017 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.rundeck:rundeck-core☕org.rundeck:rundeck-coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Rundeck is an open source automation service with a web console, command line tools and a WebAPI. Prior to version 3.3.14 and version 3.4.3, a user with admin access to the system resource type is potentially vulnerable to a CSRF attack that could cause the server to run untrusted code on all Rundeck editions. Patches are available in Rundeck versions 3.4.3 and 3.3.14.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.rundeck:rundeck-core | ≥ 3.4.0&&< 3.4.3 | 3.4.3 |
| ☕Maven | org.rundeck:rundeck-core | all versions | 3.3.14 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.rundeck:rundeck-core. 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 org.rundeck:rundeck-core to 3.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-39133 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-2021-39133 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-2021-39133. 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-2021-39133 in your dependencies?
O3 detects CVE-2021-39133 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.