14 DAY TRIAL // On May 28, Canonical published in a security notice details about Tomcat vulnerabilities for its Ubuntu 13.04, Ubuntu 12.10, Ubuntu 12.04 LTS, and Ubuntu 10.04 LTS operating systems.
According to Canonical, several security issues have been fixed in Tomcat. It’s been discovered that Tomcat incorrectly handled certain requests submitted using chunked transfer encoding.
A remote attacker could have used this flaw to cause the Tomcat server to stop responding, resulting in a denial of service.
For a more detailed description of the security problems, you can visit Canonical's security notification.
Users can simply fix the security flaws by upgrading the operating systems to the latest libtomcat7-java and libtomcat6-java packages, specific to each distribution.
A normal system update, executed with the Update Manager, will implement all the necessary changes. A complete system restart is not necessary.