Apache Tomcat 4.1.0 through 4.1.39, 5.5.0 through 5.5.27, 6.0.0 through 6.0.18, and possibly earlier versions normalizes the target pathname before filtering the query string when using the RequestDispatcher method, which allows remote attackers to bypass intended access restrictions and conduct directory traversal attacks via .. (dot dot) sequences and the WEB-INF directory in a Request.

Apache Tomcat 4.1.0 through 4.1.39, 5.5.0 through 5.5.27, and 6.0.0 through 6.0.18, when the Java AJP connector and mod_jk load balancing are used, allows remote attackers to cause a denial of service (application outage) via a crafted request with invalid headers, related to temporary blocking of connectors that have encountered errors, as demonstrated by an error involving a malformed HTTP Host header.

Apache Tomcat 4.1.0 through 4.1.39, 5.5.0 through 5.5.27, and 6.0.0 through 6.0.18, when FORM authentication is used, allows remote attackers to enumerate valid usernames via requests to /j_security_check with malformed URL encoding of passwords, related to improper error checking in the (1) MemoryRealm, (2) DataSourceRealm, and (3) JDBCRealm authentication realms, as demonstrated by a % (percent) value for the j_password parameter.

Cross-site scripting (XSS) vulnerability in jsp/cal/cal2.jsp in the calendar application in the examples web application in Apache Tomcat 4.1.0 through 4.1.39, 5.5.0 through 5.5.27, and 6.0.0 through 6.0.18 allows remote attackers to inject arbitrary web script or HTML via the time parameter, related to "invalid HTML."

Apache Tomcat 4.1.0 through 4.1.37, 5.5.0 through 5.5.26, and 6.0.0 through 6.0.16, when a RequestDispatcher is used, performs path normalization before removing the query string from the URI, which allows remote attackers to conduct directory traversal attacks and read arbitrary files via a .. (dot dot) in a request parameter.

Cross-site scripting (XSS) vulnerability in Apache Tomcat 5.5.9 through 5.5.26 and 6.0.0 through 6.0.16 allows remote attackers to inject arbitrary web script or HTML via the name parameter (aka the hostname attribute) to host-manager/html/add.

Apache Tomcat 5.5.11 through 5.5.25 and 6.0.0 through 6.0.15, when the native APR connector is used, does not properly handle an empty request to the SSL port, which allows remote attackers to trigger handling of "a duplicate copy of one of the recent requests," as demonstrated by using netcat to send the empty request.

Apache Tomcat 6.0.0 through 6.0.15 processes parameters in the context of the wrong request when an exception occurs during parameter processing, which might allow remote attackers to obtain sensitive information, as demonstrated by disconnecting during this processing in order to trigger the exception.

The default catalina.policy in the JULI logging component in Apache Tomcat 5.5.9 through 5.5.25 and 6.0.0 through 6.0.15 does not restrict certain permissions for web applications, which allows attackers to modify logging configuration options and overwrite arbitrary files, as demonstrated by changing the (1) level, (2) directory, and (3) prefix attributes in the org.apache.juli.FileHandler handler.