Microsoft has been caught out for a second time after a hotfix it reissued this weekend, due to problems with the original, caused even more headaches for network managers.
Over the weekend Microsoft released an update of a security bulletin originally sent out on 6 June.
It warned that the 6 June patch for Exchange 5.5 or 2000 contained "two issues that necessitated updating the patch".
The most recent advisory suggests that administrators "immediately install" a new patch issued on Saturday, because it emerged that the original left a number of security holes open on the Exchange server.
The vulnerability in question would allow the execution of HTML-based attachments handled by Outlook Web Access, potentially allowing a hacker to execute script on the server, allowing the "manipulation of messages or folders".
But since the weekend's reissue of the fix, a growing number of reports have been circulating insisting that the new patch causes Exchange servers to hang. Some have likened the effect to a DoS attack on the mail server, as mail floods the external servers when it is rejected by the internal machines.
Yesterday Microsoft released another update which claims to fix the problems caused by the other two patches. The latest advisory is available here.
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