On July 23, Canonical published in a security notice details about OpenJDK 6 vulnerabilities for its Ubuntu 12.04 LTS and Ubuntu 10.04 LTS operating systems.
According to Canonical, several security issues have been fixed in OpenJDK 7.
For example, several vulnerabilities have been discovered in the OpenJDK JRE related to information disclosure and data integrity. An attacker could exploit them to expose sensitive data over the network.
For a more detailed description of the security problems, you can visit Canonical's security notification.
The security flaws can be fixed if you upgrade your system(s) to the latest openjdk package, specific to each distribution. To apply the update, run the Update Manager application.
In general, a standard system update will make all the necessary changes. A system restart will be necessary to implement the changes.