Vulnerability

Weakness in an information system, system security procedures, internal controls, or implementation that could be exploited or triggered by a threat source.
SOURCE: SP 800-53; SP 800-53A; SP 800-37; SP 800-60; SP 800-115; FIPS 200
A weakness in a system, application, or network that is subject to exploitation or misuse.
SOURCE: SP 800-61
Weakness in an information system, system security procedures, internal controls, or implementation that could be exploited by a threat source.
SOURCE: CNSSI-4009