Final answer:
In the CVSS string, AV:N indicates a vulnerability can be exploited remotely over a network, representing a high level of risk due to its reachability without needing physical or local network access.
Step-by-step explanation:
In the Common Vulnerability Scoring System (CVSS) string CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N, the segment AV:N indicates that an attacker may exploit the vulnerability remotely over a network. This is considered the most serious value for this particular metric within the CVSS framework. The 'AV' stands for Access Vector, and when set to 'N' for Network, it communicates that no physical access to the device or local network access is necessary, increasing the potential reach of the attack. This makes remote exploitation more dangerous, as more systems could be at risk, regardless of their location. In contrast, other Access Vector values like 'A' for Adjacent or 'L' for Local would indicate a significantly reduced attack surface, as they require the attacker to have some form of closer access to the target system.