CVE-2009-0033

CVE-2009-0033 is a medium-severity vulnerability in Apache Tomcat with a CVSS 2.0 base score of 5.0. Its EPSS exploit-prediction score of 10% places it in the 95th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

• Severity: Medium (CVSS 2.0 base score 5.0)
• EPSS exploit prediction: 10% (95th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-20
• Affected product: Apache Tomcat
• Published: 2009-06-05
• Last modified: 2026-06-16

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.

Frequently asked questions

What is 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.

How severe is CVE-2009-0033?

CVE-2009-0033 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2009-0033 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-0033?

CVE-2009-0033 primarily affects Apache Tomcat. In total, 87 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-0033?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2009-0033 published?

CVE-2009-0033 was published on 2009-06-05 and last updated on 2026-06-16.

References

• http://jvn.jp/en/jp/JVN87272440/index.html
• http://lists.apple.com/archives/security-announce/2010//Mar/msg00001.html
• http://lists.opensuse.org/opensuse-security-announce/2009-07/msg00002.html
• http://marc.info/?l=bugtraq&m=127420533226623&w=2
• http://marc.info/?l=bugtraq&m=129070310906557&w=2
• http://marc.info/?l=bugtraq&m=133469267822771&w=2
• http://marc.info/?l=bugtraq&m=136485229118404&w=2
• http://secunia.com/advisories/35326
• http://secunia.com/advisories/35344
• http://secunia.com/advisories/35685
• http://secunia.com/advisories/35788
• http://secunia.com/advisories/37460
• http://secunia.com/advisories/42368
• http://securitytracker.com/id?1022331
• http://sunsolve.sun.com/search/document.do?assetkey=1-26-263529-1
• http://support.apple.com/kb/HT4077
• http://svn.apache.org/viewvc?rev=742915&view=rev
• http://svn.apache.org/viewvc?rev=781362&view=rev
• http://tomcat.apache.org/security-4.html
• http://tomcat.apache.org/security-5.html
• http://tomcat.apache.org/security-6.html
• http://www.debian.org/security/2011/dsa-2207
• http://www.mandriva.com/security/advisories?name=MDVSA-2009:136
• http://www.mandriva.com/security/advisories?name=MDVSA-2009:138
• http://www.mandriva.com/security/advisories?name=MDVSA-2010:176
• http://www.securityfocus.com/archive/1/504044/100/0/threaded
• http://www.securityfocus.com/archive/1/507985/100/0/threaded
• http://www.securityfocus.com/bid/35193
• http://www.vmware.com/security/advisories/VMSA-2009-0016.html
• http://www.vupen.com/english/advisories/2009/1496

Affected products (87)

• cpe:2.3:a:apache:tomcat:4.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.1:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.2:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.3:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.3:beta:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.4:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.5:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.6:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.7:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.8:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.9:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.9:beta:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.10:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.11:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.12:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.13:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.14:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.15:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.16:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.17:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.18:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.19:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.20:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.21:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.22:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.23:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.24:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.25:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.26:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.27:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.28:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.29:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.30:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.31:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.32:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.33:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.34:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.35:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.36:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:4.1.37:*:*:*:*:*:*:*

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