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HIGH severity

CVE-2011-0534 — tomcat

HIGHFix: apache/tomcat@0084470

CVE-2011-0534 is a high-severity (CVSS 7.5) CWE-399 vulnerability in org.apache.tomcat:tomcat. A fix is available for org.apache.tomcat:tomcat — see the affected versions and patch details below.

Apache Tomcat does not enforce the maxHttpHeaderSize limit

Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Oct 27, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
7.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs95th percentile — riskier than 95% of all scored CVEsHighest risk
5.37%9.84%14.3%18.8%16.3%7.9%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected
☕org.apache.tomcat:tomcat☕org.apache.tomcat:tomcat

Real-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 7.0.0 through 7.0.6 and 6.0.0 through 6.0.30 does not enforce the maxHttpHeaderSize limit for requests involving the NIO HTTP connector, which allows remote attackers to cause a denial of service (OutOfMemoryError) via a crafted request.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.apache.tomcat:tomcat≥ 6.0.0&&< 6.0.326.0.32org.apache.tomcat:tomcat:6.0.32
☕Mavenorg.apache.tomcat:tomcat≥ 7.0.0&&< 7.0.87.0.8org.apache.tomcat:tomcat:7.0.8

Affected Products

1 product · 34 configurations
Application
tomcatapache
34 versions
6.0.06.0.16.0.26.0.36.0.46.0.56.0.66.0.76.0.86.0.96.0.106.0.11

Detection & mitigation playbook

Open-source dependency

  1. Detect

    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.

  2. Fix

    Update org.apache.tomcat:tomcat to 6.0.32 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2011-0534 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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.

Red HatModerate
ProductFixed inAdvisory
JBEWS 1.0 for RHEL 4tomcat6-0:6.0.24-11.patch_03.ep5.el4RHSA-2011:0348
Red Hat Enterprise Linux 6tomcat6-0:6.0.24-24.el6_0RHSA-2011:0335
Red Hat JBoss Web Server 1.0see advisoryRHSA-2011:0350
Ubuntu
USN-1097-1Ubuntu

Frequently Asked Questions

Apache Tomcat 7.0.0 through 7.0.6 and 6.0.0 through 6.0.30 does not enforce the maxHttpHeaderSize limit for requests involving the NIO HTTP connector, which allows remote attackers to cause a denial of service (OutOfMemoryError) via a crafted request.
O3 Security · Impact-Aware SCA

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CVE-2011-0534: tomcat DoS — Fixed in 6.0.32