On March 19, Canonical published in a security notice details about an NSS vulnerability for its Ubuntu 12.10, Ubuntu 12.04 LTS, Ubuntu 11.10, Ubuntu 10.04 LTS, and Ubuntu 8.04 LTS operating systems.
According to Canonical, Perl could have been made to stop responding, if it received specially crafted input.
It was discovered that Perl incorrectly handled hashing when using user-provided hash keys. An attacker could have used this flaw to perform a denial of service attack against software written in Perl.
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 perl 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 not be necessary to implement the changes.