What is CVE-2009-0033?

CVE-2009-0033 is a vulnerability in Apache Tomcat, classified under Improper Input Validation. Published 2009-06-05.

Is CVE-2009-0033 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Improper input validation in Apache Tomcat

CVE-2009-0033

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.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2009-06-05 · last modified 2026-06-16.

CVSS v2 metric

CVSS v2 base score 5.0 (Medium). Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P. This CVE predates CVSS v3 and has no v3 score from NVD.

EPSS exploit prediction

EPSS: 0.101 (95.5th percentile), scored 2026-10-02.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 95th percentile — 95.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.101 · newest: 0.101 · change: 0.000

Affected products

Apache Tomcat — versions 4.1.0, 4.1.1, 4.1.2

Weakness classification (CWE)

CWE-20 — Improper Input Validation

Public proof-of-concept exploits

ARPSyndicate/cve-scores

References

tomcat.apache.org/security-4.html (Patch, Vendor Advisory)
marc.info/ (vendor-advisory)
secunia.com/advisories/35326 (Vendor Advisory, third-party-advisory)
www.mandriva.com/security/advisories (vendor-advisory)
www.redhat.com/archives/fedora-package-announce/2009-November/msg01246.html (vendor-advisory)
www.debian.org/security/2011/dsa-2207 (vendor-advisory)
secunia.com/advisories/35344 (Vendor Advisory, third-party-advisory)
marc.info/ (vendor-advisory)
secunia.com/advisories/37460 (third-party-advisory)
www.vupen.com/english/advisories/2010/3056 (vdb-entry)

Frequently asked questions

What is CVE-2009-0033?: CVE-2009-0033 is a vulnerability in Apache Tomcat, classified under Improper Input Validation. Published 2009-06-05.
Is CVE-2009-0033 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.