CVE-2016-6816

The code in Apache Tomcat 9.0.0.M1 to 9.0.0.M11, 8.5.0 to 8.5.6, 8.0.0.RC1 to 8.0.38, 7.0.0 to 7.0.72, and 6.0.0 to 6.0.47 that parsed the HTTP request line permitted invalid characters. This could be exploited, in conjunction with a proxy that also permitted the invalid characters but with a different interpretation, to inject data into the HTTP response. By manipulating the HTTP response the attacker could poison a web-cache, perform an XSS attack and/or obtain sensitive information from requests other then their own.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2016-6816 has a CVSS score of 7.1 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.0.0.M12, 8.5.8, 8.0.39, 7.0.73, 6.0.48); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2016-6816? CVE-2016-6816 is a high-severity improper input validation vulnerability in org.apache.tomcat:tomcat-coyote (maven), affecting versions >= 9.0.0.M1, <= 9.0.0.M11. It is fixed in 9.0.0.M12, 8.5.8, 8.0.39, 7.0.73, 6.0.48. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2016-6816? CVE-2016-6816 has a CVSS score of 7.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of org.apache.tomcat:tomcat-coyote are affected by CVE-2016-6816? org.apache.tomcat:tomcat-coyote (maven) versions >= 9.0.0.M1, <= 9.0.0.M11 is affected.
4. Is there a fix for CVE-2016-6816? Yes. CVE-2016-6816 is fixed in 9.0.0.M12, 8.5.8, 8.0.39, 7.0.73, 6.0.48. Upgrade to this version or later.
5. Is CVE-2016-6816 exploitable, and should I be worried? Whether CVE-2016-6816 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2016-6816 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2016-6816?
   • Upgrade org.apache.tomcat:tomcat-coyote to 9.0.0.M12 or later
   • Upgrade org.apache.tomcat:tomcat-coyote to 8.5.8 or later
   • Upgrade org.apache.tomcat:tomcat-coyote to 8.0.39 or later
   • Upgrade org.apache.tomcat:tomcat-coyote to 7.0.73 or later
   • Upgrade org.apache.tomcat:tomcat-coyote to 6.0.48 or later

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