ZDF
Sign inSign up

Vulnerabilities

Vulnerability · 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 attac…

Published Jun 5, 2009 · catalog updated Jun 16, 2026 · the affected product

Last checked Nov 3, 2026. A connected source was read within the last 7 days.

Check this week

CVE-2009-0033 is not in CISA KEV. FIRST estimates a 10.05% chance of exploitation in the next 30 days. Check whether you run the affected product.

Gaps on this record

  • No plain product name is stored. The page cannot tell you which product to check.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium5.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
10.05%
Remediation
Advisory link
Affected products
cpe apache/tomcat

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe apache/tomcat4.1.0
  • cpe apache/tomcat4.1.1
  • cpe apache/tomcat4.1.2
  • cpe apache/tomcat4.1.3
  • cpe apache/tomcat4.1.4

How to fix CVE-2009-0033

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2009-0033 is not in CISA KEV. FIRST estimates a 10.05% chance of exploitation in the next 30 days. Check whether you run the affected product.

Which versions are affected?

Compare what you have installed with 4.1.0, 4.1.1, 4.1.2, 4.1.3, 4.1.4. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-20: Improper Input Validation. EPSS 10.05%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Apache Tomcat security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 5, 2009 · Monitored products — critical

    Detected

    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

  2. Jun 16, 2026 · Monitored products — critical

    Updated

    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

Sources

  • FIRST EPSSExploitation probabilityCVE-2009-0033

    30-day exploitation probability 10.05%

    first.org
  • Monitored products — criticalVendor advisoryCVE-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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 3, 2026
  • Monitored products — criticalNov 3, 2026