CVE-2009-0033 — tomcat
CVE-2009-0033 is a Improper Input Validation vulnerability in org.apache.tomcat:tomcat. EPSS puts its 30-day exploitation probability at 10.1% (95th percentile). No vendor fix is recorded yet; mitigation options are listed below.
Apache Tomcat Denial of Service via Malformed Request Headers
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.
Real-World Exposure
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
Apache Tomcat 4.1.0 through 4.1.39, 5.5.0 through 5.5.27, and 6.0.0 through 6.0.18, when the Java AJP connector and mod_jk load balancing are used, allows remote attackers to cause a denial of service (application outage) via a crafted request with invalid headers, related to temporary blocking of connectors that have encountered errors, as demonstrated by an error involving a malformed HTTP Host header.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat:tomcat | ≥ 4.1.0 | No fix |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 5.5.0 | No fix |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 6.0.0 | No fix |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of org.apache.tomcat:tomcat has shipped for CVE-2009-0033 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2009-0033 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2009-0033. 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.
| Product | Fixed in | Advisory |
|---|---|---|
| JBEWS 1.0 for RHEL 4 | tomcat5-0:5.5.23-1.patch07.19.ep5.el4 | RHSA-2009:1454 |
| JBEWS 1.0 for RHEL 4 | tomcat6-0:6.0.18-11.3.ep5.el4 | RHSA-2009:1506 |
| Red Hat Certificate System 7.3 | ant-0:1.6.5-1jpp_1rh | RHSA-2010:0602 |
| Red Hat Developer Suite V.3 | tomcat5-0:5.5.23-0jpp_18rh | RHSA-2009:1563 |
| Red Hat Enterprise Linux 5 | tomcat5-0:5.5.23-0jpp.7.el5_3.2 | RHSA-2009:1164 |
| Red Hat Network Satellite Server v 5.1 | tomcat5-0:5.0.30-0jpp_16rh | RHSA-2009:1617 |
| Red Hat Network Satellite Server v 5.2 | tomcat5-0:5.5.23-0jpp_18rh | RHSA-2009:1616 |
| RHAPS Version 2 for RHEL 4 | tomcat5-0:5.5.23-0jpp_4rh.16 | RHSA-2009:1562 |
Frequently Asked Questions
Is CVE-2009-0033 in your dependencies?
O3 Security finds CVE-2009-0033 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.