The Collaborative International Dictionary of English v.0.48:

Vulnerability \Vul`ner*a*bil"i*ty\, n.
   The quality or state of being vulnerable; vulnerableness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vulnerability
    n 1: the state of being vulnerable or exposed; "his
         vulnerability to litigation"; "his exposure to ridicule"
         [syn: vulnerability, exposure]
    2: susceptibility to injury or attack [ant: invulnerability]

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "vulnerability":
   ad lib, assailability, breakability, breakableness, brittleness,
   chink, crackability, crackableness, crispness, crumbliness,
   crushability, crushableness, delicacy, disqualification, exposure,
   extemporaneousness, fissility, flimsiness, fracturableness,
   fragility, frailty, frangibility, friability, heel of Achilles,
   improvisation, incapability, incompetence, lacerability,
   lack of preparation, liability, nonpreparation, nonpreparedness,
   openness, penetrability, planlessness, pregnability, soft spot,
   susceptibility, susceptivity, unfitness, unfittedness,
   unpreparedness, unqualification, unqualifiedness, unreadiness,
   unsuitability, unsuitableness, unsuitedness, vincibility,
   vulnerable point, weak link, weak point, weakness



The Free On-line Dictionary of Computing (30 December 2018):

vulnerability
security vulnerability

    A bug or feature of a system that exposes it to
   possible attack, a flaw in the system's security.

   A common example of a vulnerability due to a bug is buffer
   overrun, where carefully constructed input can allow an
   attacker to insert arbitrary code into a running program and
   have it executed.

   The most serious vulnerabilities are those in network
   software, especially if they exploit traffic that is allowed
   through the firewall like HTTP, for example exploiting a
   bug in a web browser.

   The Open Source Vulnerability Database lists many
   vulnerabilities.

   (2007-12-02)