On January 14, in a security notice Canonical published details about an NSPR vulnerability for its Ubuntu 12.10, Ubuntu 12.04 LTS, Ubuntu 12.04 LTS, Ubuntu 11.10, and Ubuntu 10.04 LTS operating systems.According to Canonical, NSPR has been updated in order to work with the new NSS.
In USN-1687-1 notification, Canonical fixed vulnerability NSS. This update provides the NSPR needed to use the new NSS.
According to Canonical, a remote attacker would have been able to perform a man-in-the-middle attack, which could have exposed sensitive information.
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 libnspr4-0d package, 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.