On October 25, in a security notice Canonical published details about OpenJDK vulnerabilities for its Ubuntu 12.10, Ubuntu 12.04 LTS, Ubuntu 11.10, Ubuntu 11.04, and Ubuntu 10.04 LTS operating systems.
According to Canonical, several security issues were fixed in OpenJDK related to information
disclosure and data integrity, and related to confidentiality via unknown vectors from Libraries. A local attacker could have exploited these problems in order to cause 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 openjdk-7-jre, openjdk-7-jre-headless, openjdk-7-jre-lib, icedtea-7-jre-cacao, icedtea-7-jre-jamvm, AND openjdk-7-jre-zero, 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.