CVE-2009-0033: Apache Tomcat

Medium severity, CVSS 5.0. EPSS: 10.1% chance of exploitation in the next 30 days.

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 products

• Apache Tomcat: version 4.1.0 only; version 4.1.1 only; version 4.1.2 only; version 4.1.3 only; version 4.1.4 only; version 4.1.5 only; …

Published 2009-06-05. Last modified 2026-06-16.