CVE-2016-6817 Improper Restriction of Operations within the Bounds of a Memory Buffer in Apache Tomcat

What is CVE-2016-6817?

CVE-2016-6817 is a high-severity denial of service vulnerability in Apache Tomcat, published on 10 Aug 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

The HTTP/2 header parser in Apache Tomcat 9.0.0.M1 to 9.0.0.M11 and 8.5.0 to 8.5.6 entered an infinite loop if a header was received that was larger than the available buffer. This made a denial of service attack possible.

Weakness: CWE-119, CWE-835

Which versions are affected by CVE-2016-6817?

4 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-2016-6817?

Upgrade org.apache.tomcat:tomcat to a fixed version for your release line: 8.5.8 or 9.0.0.M12.

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-2016-6817 being exploited?

There is no known exploitation of CVE-2016-6817 in the wild and no public exploit code.

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 GHSA-698c-2x4j-g9gq.