Task: Analyze the tweet's emotional connotations and classify it as either 'neutral or no emotion' or as one or more of the specified emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best portray the tweeter's mental state.
Tweet: They are building a shell command on a server, combining that with user input, and then executing that in a shell on the client. #shudder
This tweet contains emotions: 
fear, joy