CVE-2016-8745
HIGHCVE-2016-8745 is a high-severity (CVSS 7.5) vulnerability in org.apache.tomcat:tomcat-util. O3 Security confirms whether CVE-2016-8745 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Concurrent Execution using Shared Resource with Improper Synchronization in Apache Tomcat
Blast Radius
org.apache.tomcat:tomcat-util☕org.apache.tomcat:tomcat-util☕org.apache.tomcat:tomcat-util☕org.apache.tomcat:tomcat-util☕org.apache.tomcat:tomcat-utilReal-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
A bug in the error handling of the send file code for the NIO HTTP connector in Apache Tomcat 9.0.0.M1 to 9.0.0.M13, 8.5.0 to 8.5.8, 8.0.0.RC1 to 8.0.39, 7.0.0 to 7.0.73 and 6.0.16 to 6.0.48 resulted in the current Processor object being added to the Processor cache multiple times. This in turn meant that the same Processor could be used for concurrent requests. Sharing a Processor can result in information leakage between requests including, not not limited to, session ID and the response body. The bug was first noticed in 8.5.x onwards where it appears the refactoring of the Connector code for 8.5.x onwards made it more likely that the bug was observed. Initially it was thought that the 8.5.x refactoring introduced the bug but further investigation has shown that the bug is present in all currently supported Tomcat versions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 9.0.0.M1&&< 9.0.0.M14 | 9.0.0.M14 |
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 8.5.0&&< 8.5.9 | 8.5.9 |
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 8.0.0-RC1&&< 8.0.41 | 8.0.41 |
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 7.0.0&&< 7.0.75 | 7.0.75 |
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 6.0.16&&< 6.0.50 | 6.0.50 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.tomcat:tomcat-util. 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.tomcat:tomcat-util to 9.0.0.M14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-8745 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-2016-8745 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-2016-8745. 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-2016-8745 in your dependencies?
O3 detects CVE-2016-8745 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.