Jim Meyering discovered that tar did not properly verify the validity of certain header fields in a GNU tar archive. By tricking an user into processing a specially crafted tar archive, this could be exploited to execute arbitrary code with the privileges of the user.
The tar version in Ubuntu 4.10 is not affected by this vulnerability.
Solution: The problem can be corrected by upgrading the affected package to version 1.14-2ubuntu0.1 (for Ubuntu 5.04), or 1.15.1-2ubuntu0.1 (for Ubuntu 5.10). In general, a standard system upgrade is sufficient to effect the necessary changes.