An elevation of privilege vulnerability exists in Microsoft Exchange Server. An attacker who successfully exploited this vulnerability could attempt to impersonate any other user of the Exchange server. To exploit the vulnerability, an attacker would need to execute a man-in-the-middle attack to forward an authentication request to a Microsoft Exchange Server, thereby allowing impersonation of another Exchange user. To address this vulnerability, a registry value which enables NTLM authentication on the network loopback adapter needs to be removed. Future cumulative updates will ensure that this registry setting is configured correctly during installation of the cumulative update.

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