The problem can be corrected by upgrading the affected package to version 3.8.3-3ubuntu0.3 (for Ubuntu 4.10), or 3.8.3-3ubuntu0.4 (for Ubuntu 5.04). In general, a standard system upgrade is sufficient to effect the necessary changes.
Details follow:
It was discovered that certain invalid BGP packets triggered an infinite loop in tcpdump, which caused tcpdump to stop working. This could be abused by a remote attacker to bypass tcpdump analysis of network traffic.