CVE-2011-4858 Improper Input Validation in Apache Tomcat

What is CVE-2011-4858?

CVE-2011-4858 is a medium-severity denial of service vulnerability in Apache Tomcat, published on 5 Jan 2012. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Apache Tomcat before 5.5.35, 6.x before 6.0.35, and 7.x before 7.0.23 computes hash values for form parameters without restricting the ability to trigger hash collisions predictably, which allows remote attackers to cause a denial of service (CPU consumption) by sending many crafted parameters.

Weakness: CWE-399

Which versions are affected by CVE-2011-4858?

6 open source packages ship an affected version, including org.apache.tomcat:tomcat. It affects 1 product.

Products include Apache Tomcat.

How do I fix CVE-2011-4858?

Upgrade org.apache.tomcat:tomcat to a fixed version for your release line: 5.5.35, 6.0.35 or 7.0.23.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2011-4858 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2011-4858 exists.

Public exploit code: 1 Metasploit module and 1 Exploit-DB entry.

Other vulnerabilities in Apache Tomcat

• CVE-2025-24813 Apache Tomcat Path Equivalence Exploited Critical 10.0
• CVE-2016-8735 Apache Tomcat Remote Code Execution Exploited Critical 9.8
• CVE-2017-12617 Apache Tomcat Remote Code Execution Exploited High 8.1
• CVE-2017-12615 Apache Tomcat on Windows Remote Code Execution Exploited High 8.1
• CVE-2026-34486 Apache Tomcat Missing Encryption of Sensitive Data Exploited High 7.5

All Apache Tomcat vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as CVE-2011-4084, GHSA-wr3m-gw98-mc3j.