Final answer:
Shared key authentication is a security risk in wireless LANs because it uses a common key that can be intercepted by attackers, enabling unauthorized access.
Step-by-step explanation:
Shared key authentication in a wireless local area network (LAN) is considered a security risk because shared keys can be easily intercepted by unauthorized individuals. When using shared key authentication, the same key or password is used by all clients on the network to authenticate with the access point. This key is shared during the authentication process and can be captured by an attacker, especially if the network uses weak encryption protocols. If an attacker obtains the key, they can gain unauthorized access to the network, potentially leading to data breaches and other security issues.