CVE-2017-5651

In Apache Tomcat 9.0.0.M1 to 9.0.0.M18 and 8.5.0 to 8.5.12, the refactoring of the HTTP connectors introduced a regression in the send file processing. If the send file processing completed quickly, it was possible for the Processor to be added to the processor cache twice. This could result in the same Processor being used for multiple requests which in turn could lead to unexpected errors and/or response mix-up.

CVE-2017-5651 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. 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.M19, 8.5.13); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2017-5651? CVE-2017-5651 is a critical-severity security vulnerability in org.apache.tomcat:tomcat-coyote (maven), affecting versions >= 9.0.0.M1, <= 9.0.0.M18. It is fixed in 9.0.0.M19, 8.5.13.
2. How severe is CVE-2017-5651? CVE-2017-5651 has a CVSS score of 9.8 (Critical). 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 packages are affected by CVE-2017-5651?
   • org.apache.tomcat:tomcat-coyote (maven) (versions >= 9.0.0.M1, <= 9.0.0.M18)
   • org.apache.tomcat.embed:tomcat-embed-core (maven) (versions >= 9.0.0.M1, <= 9.0.0.M18)
4. Is there a fix for CVE-2017-5651? Yes. CVE-2017-5651 is fixed in 9.0.0.M19, 8.5.13. Upgrade to this version or later.
5. Is CVE-2017-5651 exploitable, and should I be worried? Whether CVE-2017-5651 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-2017-5651 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-2017-5651?
   • Upgrade org.apache.tomcat:tomcat-coyote to 9.0.0.M19 or later
   • Upgrade org.apache.tomcat:tomcat-coyote to 8.5.13 or later
   • Upgrade org.apache.tomcat.embed:tomcat-embed-core to 9.0.0.M19 or later
   • Upgrade org.apache.tomcat.embed:tomcat-embed-core to 8.5.13 or later