Which of the following is most likely associated with introducing vulnerabilities on a corporate network...

Shadow IT refers to the use of information technology systems, devices, software, applications, and services without explicit IT department approval. This is the most likely cause of introducing vulnerabilities on a corporate network by deploying unapproved software, as such software may not have been vetted for security compliance, increasing the risk of vulnerabilities.

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CompTIA Security+ SY0-701 Course Content: The concept of Shadow IT is discussed as a significant risk due to the introduction of unapproved and potentially vulnerable software into the corporate network​​.