CVE-2019-17569
MEDIUMCVE-2019-17569 is a medium-severity (CVSS 4.8) CWE-444 vulnerability in org.apache.tomcat.embed:tomcat-embed-core. O3 Security confirms whether CVE-2019-17569 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Potential HTTP request smuggling in Apache Tomcat
Real-World Exposure
org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat:tomcat☕org.apache.tomcat:tomcat☕org.apache.tomcat:tomcatReal-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
The refactoring present in Apache Tomcat 9.0.28 to 9.0.30, 8.5.48 to 8.5.50 and 7.0.98 to 7.0.99 introduced a regression. The result of the regression was that invalid Transfer-Encoding headers were incorrectly processed leading to a possibility of HTTP Request Smuggling if Tomcat was located behind a reverse proxy that incorrectly handled the invalid Transfer-Encoding header in a particular manner. Such a reverse proxy is considered unlikely.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 7.0.98&&< 7.0.100 | 7.0.100 |
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 8.5.48&&< 8.5.51 | 8.5.51 |
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 9.0.28&&< 9.0.31 | 9.0.31 |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 7.0.98&&< 7.0.100 | 7.0.100 |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 8.5.48&&< 8.5.51 | 8.5.51 |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 9.0.28&&< 9.0.31 | 9.0.31 |
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.embed:tomcat-embed-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.tomcat.embed:tomcat-embed-core to 7.0.100 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-17569 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-2019-17569 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-2019-17569. 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.
This flaw did not affect the versions of Tomcat as shipped with Red Enterprise Linux 5, 6, 7 and 8, as they did not include the vulnerable code, which was introduced in a later version of the package. OpenDaylight in Red Hat OpenStack 10 & 13 was in technical preview status, because of this no fixes will be released…
Frequently Asked Questions
Is CVE-2019-17569 in your dependencies?
O3 detects CVE-2019-17569 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.