CVE-2021-33813 is a high-severity (CVSS 7.5) XML External Entity (XXE) vulnerability in org.jdom:jdom2. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2021-33813 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
XML External Entity (XXE) Injection in JDOM
Real-World Exposure
org.jdom:jdom2☕org.jdom:jdomReal-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
An XXE issue in SAXBuilder in JDOM through 2.0.6 allows attackers to cause a denial of service via a crafted HTTP request.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.jdom:jdom2 | all versions | 2.0.6.1 |
| ☕Maven | org.jdom:jdom | all versions | No fix |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jdom:jdom2. 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.jdom:jdom2 to 2.0.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-33813 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-2021-33813 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-2021-33813. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
In OpenShift Container Platform (OCP), the hive and hadoop components that comprise the OCP metering stack, ship the vulnerable version of jdom. Since the release of OCP 4.6, the metering product has been deprecated [1], hence the affected components are marked as wontfix. This may be fixed in the future. This flaw is…
Frequently Asked Questions
Is CVE-2021-33813 in your dependencies?
O3 detects CVE-2021-33813 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.