The US Cybersecurity and Infrastructure Security Agency (CISA) has made a directive available to mitigate the vulnerability in Microsoft Exchange servers, but users are being denied access due to authentication issues.
According to CISA, this directive is essential to address an active security threat affecting multiple organizations worldwide. The official directive can be accessed at http://www.cisa.gov/news-events/directives/ed-25-02-mitigate-microsoft-exchange-vulnerability.
However, some users have reported encountering access denied messages when attempting to retrieve the directive from this server. This issue may be attributed to authentication restrictions or technical problems on the server end.
Source: https://www.cisa.gov/news-events/directives/ed-25-02-mitigate-microsoft-exchange-vulnerability