Multiple vulnerabilities and a security issue have been reported in Apache Tomcat, which can be exploited by malicious users to disclose sensitive information or manipulate certain data and by malicious people to cause a DoS (Denial of Service) or disclose sensitive information.

1) An error exists when processing invalid HTTP headers received via the Java AJP connector. This can be exploited to close AJP connections and temporarily block a connector that is a member of a mod_jk load balancing worker.

2) An error in certain authentication classes can be exploited to potentially enumerate existing usernames via specially crafted URL-encoded passwords and brute force attacks.

Successful exploitation of this vulnerability requires that form based authentication ("j_security_check") with one of the "MemoryRealm", "DataSourceRealm", or "JDBCRealm" authentication realms is used.

3) It is possible for a web application to replace the XML parser used by Tomcat to process web.xml and tld files. In certain circumstances this may be exploited by a malicious web application to view or alter the web.xml and tld files of other web applications deployed on the Tomcat instance.

4) The server normalises the target path before removing the query string when using a "RequestDispatcher". This can be exploited to access normally restricted files via e.g. directory traversal attacks.

The vulnerabilities are reported in versions 4.1.0 through 4.1.39 and 5.5.0 through 5.5.27.

Solution
Update to version 4.1.40 or 5.5.28.

Provided and/or discovered by
The vendor credits:
1) Yoshihito Fukuyama
2) D. Matscheko and T. Hackner of SEC Consult
3) Philippe Prados
4) Iida Minehiko, Fujitsu Limited

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://tomcat.apache.org/security-4.html
http://tomcat.apache.org/security-5.html

http://marc.info/?l=tomcat-user&m=124404378413716&w=2
http://marc.info/?l=tomcat-user&m=124404378913734&w=2
http://marc.info/?l=tomcat-user&m=124412001618125&w=2
http://marc.info/?l=tomcat-user&m=124449799021571&w=2

Other references
Further details available to Secunia VIM customers

Deep Links
Links available to Secunia VIM customers