Summary
While investigating bug 64830 it was discovered that Apache Tomcat 10.0.0-M1 to 10.0.0-M9, 9.0.0-M1 to 9.0.39 and 8.5.0 to 8.5.59 could re-use an HTTP request header value from the previous stream received on an HTTP/2 connection for the request associated with the subsequent stream. While this would most likely lead to an error and the closure of the HTTP/2 connection, it is possible that information could leak between requests.
Impact
CVE-2020-17527 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-M10, 9.0.40, 8.5.60); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
org.apache.tomcat:tomcat-coyote to 10.0.0-M10 or later; org.apache.tomcat:tomcat-coyote to 9.0.40 or later; org.apache.tomcat:tomcat-coyote to 8.5.60 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2020-17527? CVE-2020-17527 is a high-severity security vulnerability in org.apache.tomcat:tomcat-coyote (maven), affecting versions >= 10.0.0-M1, < 10.0.0-M10. It is fixed in 10.0.0-M10, 9.0.40, 8.5.60.
- How severe is CVE-2020-17527? CVE-2020-17527 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.
- Which versions of org.apache.tomcat:tomcat-coyote are affected by CVE-2020-17527? org.apache.tomcat:tomcat-coyote (maven) versions >= 10.0.0-M1, < 10.0.0-M10 is affected.
- Is there a fix for CVE-2020-17527? Yes. CVE-2020-17527 is fixed in 10.0.0-M10, 9.0.40, 8.5.60. Upgrade to this version or later.
- Is CVE-2020-17527 exploitable, and should I be worried? Whether CVE-2020-17527 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
- What actually determines whether CVE-2020-17527 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.
- How do I fix CVE-2020-17527?
- Upgrade
org.apache.tomcat:tomcat-coyoteto 10.0.0-M10 or later - Upgrade
org.apache.tomcat:tomcat-coyoteto 9.0.40 or later - Upgrade
org.apache.tomcat:tomcat-coyoteto 8.5.60 or later
- Upgrade