On October 23, in a security notice, Canonical published details about a Swift vulnerability in its Ubuntu 13.04, Ubuntu 12.10, and Ubuntu 12.04 LTS operating systems.
According to the company, Swift could have caused the system to crash, had it received specially crafted requests over the network.
It has been discovered that Swift did not properly handle requests with old X-Timestamp values. An authenticated attacker could have exploited this to cause a denial of service via disk consumption.
For a more detailed description of the security problems, you can see Canonical's security notification.
The security flaws can be fixed if you upgrade your system(s) to the latest python-swift 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 and a restart is not required.