CVE-2020-13935

The payload length in a WebSocket frame was not correctly validated in Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M1 to 9.0.36, 8.5.0 to 8.5.56 and 7.0.27 to 7.0.104. Invalid payload lengths could trigger an infinite loop. Multiple requests with invalid payload lengths could lead to a denial of service.

CVE-2020-13935 has a CVSS score of 7.5 (High). 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 (10.0.0-M7, 9.0.37, 8.5.57, 7.0.105); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2020-13935? CVE-2020-13935 is a high-severity security vulnerability in org.apache.tomcat:tomcat (maven), affecting versions >= 10.0.0-M1, < 10.0.0-M7. It is fixed in 10.0.0-M7, 9.0.37, 8.5.57, 7.0.105.
2. How severe is CVE-2020-13935? CVE-2020-13935 has a CVSS score of 7.5 (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 packages are affected by CVE-2020-13935?
   • org.apache.tomcat:tomcat (maven) (versions >= 10.0.0-M1, < 10.0.0-M7)
   • org.apache.tomcat.embed:tomcat-embed-websocket (maven) (versions >= 7.0.27, < 7.0.105)
   • org.apache.tomcat:tomcat-websocket (maven) (versions >= 10.0.0-M1, < 10.0.0-M7)
4. Is there a fix for CVE-2020-13935? Yes. CVE-2020-13935 is fixed in 10.0.0-M7, 9.0.37, 8.5.57, 7.0.105. Upgrade to this version or later.
5. Is CVE-2020-13935 exploitable, and should I be worried? Whether CVE-2020-13935 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-2020-13935 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-2020-13935?
   • Upgrade org.apache.tomcat:tomcat to 10.0.0-M7 or later
   • Upgrade org.apache.tomcat:tomcat to 9.0.37 or later
   • Upgrade org.apache.tomcat:tomcat to 8.5.57 or later
   • Upgrade org.apache.tomcat:tomcat to 7.0.105 or later
   • Upgrade org.apache.tomcat.embed:tomcat-embed-websocket to 7.0.105 or later
   • Upgrade org.apache.tomcat.embed:tomcat-embed-websocket to 8.5.57 or later
   • Upgrade org.apache.tomcat.embed:tomcat-embed-websocket to 9.0.37 or later
   • Upgrade org.apache.tomcat.embed:tomcat-embed-websocket to 10.0.0-M7 or later
   • Upgrade org.apache.tomcat:tomcat-websocket to 10.0.0-M7 or later
   • Upgrade org.apache.tomcat:tomcat-websocket to 9.0.37 or later
   • Upgrade org.apache.tomcat:tomcat-websocket to 8.5.57 or later
   • Upgrade org.apache.tomcat:tomcat-websocket to 7.0.105 or later