When running on Windows with enableCmdLineArguments enabled, the CGI Servlet in Apache Tomcat 9.0.0.M1 to 9.0.17, 8.5.0 to 8.5.39 and 7.0.0 to 7.0.93 is vulnerable to Remote Code Execution due to a bug in the way the JRE passes command line arguments to Windows. The CGI Servlet is disabled by default. The CGI option enableCmdLineArguments is disable by default in Tomcat 9.0.x (and will be disabled by default in all versions in response to this vulnerability). For a detailed explanation of the JRE behaviour, see Markus Wulftange's blog (https://codewhitesec.blogspot.com/2016/02/java-and-command-line-injections-in-windows.html) and this archived MSDN blog (https://web.archive.org/web/20161228144344/https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/).
When the default servlet in Apache Tomcat versions 9.0.0.M1 to 9.0.11, 8.5.0 to 8.5.33 and 7.0.23 to 7.0.90 returned a redirect to a directory (e.g. redirecting to '/foo/' when the user requested '/foo') a specially crafted URL could be used to cause the redirect to be generated to any URI of the attackers choice.
An improper handing of overflow in the UTF-8 decoder with supplementary characters can lead to an infinite loop in the decoder causing a Denial of Service. Versions Affected: Apache Tomcat 9.0.0.M9 to 9.0.7, 8.5.0 to 8.5.30, 8.0.0.RC1 to 8.0.51, and 7.0.28 to 7.0.86.
The host name verification when using TLS with the WebSocket client was missing. It is now enabled by default. Versions Affected: Apache Tomcat 9.0.0.M1 to 9.0.9, 8.5.0 to 8.5.31, 8.0.0.RC1 to 8.0.52, and 7.0.35 to 7.0.88.
The defaults settings for the CORS filter provided in Apache Tomcat 9.0.0.M1 to 9.0.8, 8.5.0 to 8.5.31, 8.0.0.RC1 to 8.0.52, 7.0.41 to 7.0.88 are insecure and enable 'supportsCredentials' for all origins. It is expected that users of the CORS filter will have configured it appropriately for their environment rather than using it in the default configuration. Therefore, it is expected that most users will not be impacted by this issue.
Apache Tomcat through 7.0.x allows remote attackers to cause a denial of service (daemon outage) via partial HTTP requests, as demonstrated by Slowloris.