CVE-2020-13943: 
Java vulnerability analysis and mitigation

CVE-2020-13943 is a security vulnerability affecting Apache Tomcat versions 10.0.0-M1 to 10.0.0-M7, 9.0.0.M1 to 9.0.37, and 8.5.0 to 8.5.57. The vulnerability was discovered in 2020 and relates to HTTP/2 protocol implementation (CVE Mitre).

The vulnerability occurs when an HTTP/2 client connecting to Apache Tomcat exceeds the agreed maximum number of concurrent streams for a connection, violating the HTTP/2 protocol specifications. In such cases, subsequent requests made on that connection could contain HTTP headers - including HTTP/2 pseudo headers - from a previous request rather than the intended headers (Rapid7).

When successfully exploited, this vulnerability could lead to users seeing responses for unexpected resources, potentially exposing sensitive information. The vulnerability has been assigned a CVSS score of 5.3 (MEDIUM) with the vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N (NVD).

The vulnerability is remotely exploitable and requires an attacker to send malformed HTTP/2 requests that exceed the maximum concurrent streams limit. The attack complexity is considered low, requiring no special privileges or user interaction (Rapid7).

The vulnerability has been fixed in Apache Tomcat versions 8.5.58, 9.0.38, and later releases. Users are strongly recommended to upgrade to these patched versions to address the security issue (Apache Tomcat).