AFAIK the answer is no. Person A can only browse or downld files that are shared by person B & vice versa. There was a security issue that was fixed with LW version 4.8.1 so the only accessible files are those that are shared! Double-check your folders that are being shared (Tools>Options>Sharing)

But you should keep an active firewall, anti-virus program with up to date definitions, & the following programs (click green links):

ad-ware (FREE)

Spybot - Search & Destroy (FREE)

Peerguardian (FREE)

There has been a no. of viruses being found across the gnutella network, so check all files you're downlding.