Microsoft Exchange 2003 and Outlook Web Access (OWA), when configured to use NTLM authentication, does not properly reuse HTTP connections, which can cause OWA users to view mailboxes of other users when Kerberos has been disabled as an authentication method for IIS 6.0, e.g. when SharePoint Services 2.0 is installed.
secunia.com/advisories/10615
www.kb.cert.org/vuls/id/530660
www.microsoft.com/exchange/support/e2k3owa.asp
www.ntbugtraq.com/default.asp?pid=36&sid=1&A2=ind0311&L=ntbugtraq&F=P&S=&P=9281
www.securityfocus.com/bid/9118
www.securityfocus.com/bid/9409
docs.microsoft.com/en-us/security-updates/securitybulletins/2004/ms04-002
exchange.xforce.ibmcloud.com/vulnerabilities/13869
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A477