On October 1st, in a security notice Canonical published details about GNU C Library vulnerabilities for its Ubuntu 12.04 LTS, Ubuntu 11.10, Ubuntu 11.04, Ubuntu 10.04 LTS, and Ubuntu 8.04 LTS operating systems.
According to Canonical, multiple security issues were fixed in the GNU C Library. Positional arguments to the printf() family of functions were not handled properly in the GNU C Library.
An attacker could have possibly used this to cause a stack-based buffer overflow, creating a denial of service or possibly execute arbitrary code.
The security flaws can be fixed if you upgrade your system(s) to the latest libc6 package. To apply the update, run the Update Manager application.
In general, a standard system update will make all the necessary changes. After the system update, users must reboot the computer.