It was discovered that Tk could be made to overrun a buffer when loading certain images. If a user were tricked into opening a specially crafted GIF image, remote attackers could cause a denial of service or execute arbitrary code with user privileges.
The problem can be corrected by updating your system to the following package versions:
6 November 2008
A security issue affects these releases of Ubuntu and its derivatives:
It was discovered that Tk could be made to overrun a buffer when loading certain images. If a user were tricked into opening a specially crafted GIF image, remote attackers could cause a denial of service or execute arbitrary code with user privileges.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
In general, a standard system upgrade is sufficient to effect the necessary changes.