CVE-2016-8738
MEDIUMCVE-2016-8738 is a medium-severity (CVSS 5.9) Improper Input Validation vulnerability in org.apache.struts:struts2-core. O3 Security confirms whether CVE-2016-8738 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Apache Struts vulnerable to possible DoS attack when using URLValidator
Real-World Exposure
org.apache.struts:struts2-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
In Apache Struts 2.5 through 2.5.5, if an application allows entering a URL in a form field and the built-in URLValidator is used, it is possible to prepare a special URL which will be used to overload server process when performing validation of the URL.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.struts:struts2-core | ≥ 2.5.0&&< 2.5.13 | 2.5.13 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.struts:struts2-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.apache.struts:struts2-core to 2.5.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-8738 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-2016-8738 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-2016-8738. 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-2016-8738 in your dependencies?
O3 detects CVE-2016-8738 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.