Canonical published in a security notice details about the Light Display Manager vulnerability in its Ubuntu 13.10 (Saucy Salamander) operating system.According to the company, Light Display Manager could have been made to expose sensitive information locally.
It has been discovered that Light Display Manager incorrectly applied the AppArmor security profile when the Guest account was used. A local attacker could have used this issue to possibly gain access to sensitive information.
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 lightdm package specific to each distribution. To apply the new firmware, run the Update Manager application.
In general, a standard system update will make all the necessary changes. A system restart will be necessary to implement them.