Weakness in an information system, system security procedures, internal controls, or implementation that could be exploited or triggered by a threat source. Response:

A vulnerability is a flaw or weakness in a system's design, implementation, operation, or management that can be exploited by a threat to compromise security. This definition directly matches the description provided in the question.

Availability is a security objective ensuring authorized users have timely and uninterrupted access to information and systems, not a weakness.

Integrity is a security objective ensuring information is protected from unauthorized modification or destruction, not a weakness.

Confidentiality is a security objective ensuring information is protected from unauthorized disclosure, not a weakness.