Outlook Outage Hits Users as Microsoft Fixes Exploited Security Flaw

Users reported problems with Outlook’s website, app and sign-in functions on November 12, including difficulty sending and receiving email. Reports of issues began rising around 12:39 p.m. ET. By 1:09 p.m., Downdetector had logged more than 129,000 error reports. The disruption affected users across North America and may have reached other regions as well.

Microsoft said it was investigating reports that users in the Americas could not access Exchange Online mailboxes through multiple connection methods. Microsoft Teams and Copilot were also affected.

The outage came days after Microsoft issued a security fix for an Outlook flaw being exploited in real attacks. Viewing a maliciously prepared attachment with certain Outlook editions could make the program contact a network address controlled by criminals, exposing sign-in information that could be used to impersonate victims or potentially access accounts and workplace systems.

Microsoft included the fix in its November 10 security updates. Users need to install the relevant Office update: open an Office app such as Word, go to File, then Account, and choose Update Options and Update Now. In classic Outlook, the menu may be labeled Office Account. Checking Windows Update alone does not ensure this Office fix is installed.

Until updated, users were advised to avoid unexpected attachments and message files, including ones that appear to come from familiar senders. Microsoft had not provided further details about the service disruption in the available information.